BLUE COAT SYSTEMS, INC. SENIOR CONVERTIBLE NOTE

Exhibit 4.01

THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A NOTE PURCHASE AGREEMENT DATED AS OF APRIL 20, 2008, BY AND AMONG THE ISSUER AND THE OTHER PERSONS NAMED THEREIN, AS SUCH AGREEMENT MAY BE AMENDED, RESTATED OR MODIFIED FROM TIME TO TIME, AND MAY NOT BE TRANSFERRED, SOLD, ASSIGNED, PLEDGED, HYPOTHECATED OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THE PROVISIONS THEREOF, AND ANY TRANSFEREE OF THESE SECURITIES SHALL BE SUBJECT TO THE TERMS OF SUCH AGREEMENT. COPIES OF SUCH AGREEMENT ARE MAINTAINED WITH THE CORPORATE RECORDS OF THE ISSUER AND ARE AVAILABLE FOR INSPECTION AT THE PRINCIPAL OFFICES OF THE ISSUER.

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ ACT ”), OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED, SOLD OR TRANSFERRED EXCEPT PURSUANT TO (I) AN EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT, AND IN COMPLIANCE WITH APPLICABLE STATE SECURITIES LAWS OR (II) AN APPLICABLE EXEMPTION FROM REGISTRATION UNDER THE ACT AND UNDER APPLICABLE STATE SECURITIES LAWS.

FOR PURPOSES OF SECTIONS 1272, 1273 AND 1275 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED, THIS NOTE IS BEING ISSUED WITH ORIGINAL ISSUE DISCOUNT AND THE ISSUE DATE OF THIS SECURITY IS JUNE 2, 2008. A HOLDER MAY OBTAIN THE ISSUE PRICE, THE AMOUNT OF ORIGINAL ISSUE DISCOUNT, THE ISSUE DATE AND THE YIELD TO MATURITY FOR THESE NOTES BY SUBMITTING A WRITTEN REQUEST FOR SUCH INFORMATION TO BLUE COAT SYSTEMS, INC., 420 NORTH MARY AVENUE, SUNNYVALE, CALIFORNIA 94085, ATTENTION: KEVIN ROYAL.

BLUE COAT SYSTEMS, INC.

SENIOR CONVERTIBLE NOTE

FOR VALUE RECEIVED, Blue Coat Systems, Inc., a Delaware corporation (the “ Company ”), hereby promises to pay to the order of                      (“ Holder ”) the amount set forth above as the Original Principal Amount (as reduced pursuant to the terms hereof, the “ Principal ”) when due, whether upon the Maturity Date (as defined below), acceleration or otherwise (in each case in accordance with the terms hereof). This Senior Convertible Note (including all Senior Convertible Notes issued in exchange, transfer or replacement hereof, this “ Note ”) is one of an issue of Senior Convertible Notes (collectively, the “ Notes ” and such other Senior Convertible Notes, the “ Other Notes ”) issued pursuant to the Purchase Agreement (as defined below). Capitalized terms used herein and not otherwise defined have the respective meanings given them in Section 24.

1. Maturity . On the Maturity Date, the Holder shall surrender this Note to the Company and the Company shall pay to the Holder the outstanding Principal and accrued and unpaid Late Charges, if any, on such Principal to but excluding the Maturity Date. The “ Maturity Date ” shall be June 2, 2013.

2. Interest; Interest Rate . This Note shall not bear interest (other than any Late Charge).

3. Conversion . This Note shall be convertible into shares of the Company’s Common Stock on the terms and conditions set forth in this Section 3.

(a) Conversion Right . At any time or times on or after the Issuance Date, the Holder shall be entitled to convert all (or any portion equal to $1,000 or any integral multiple of $1,000 in excess thereof) of the outstanding and unpaid Conversion Amount into fully paid, validly issued and nonassessable shares of Common Stock in accordance with Section 3(c), at the Conversion Rate. The Company shall not issue any fraction of a share of Common Stock upon any conversion. If the issuance would result in the issuance of a fraction of a share of Common Stock, the Company shall round such fraction to the nearest whole share. The Company shall pay any and all taxes and fees that may be payable with respect to the issuance and delivery of Common Stock upon conversion of any Conversion Amount.

(b) Conversion Rate . The number of shares of Common Stock issuable upon conversion of any Conversion Amount pursuant to this Note shall be determined by dividing (x) such Conversion Amount by (y) the then applicable Conversion Price (the “ Conversion Rate ”).

(i) “ Conversion Amount ” means the portion of the Principal to be converted, redeemed or otherwise with respect to which this determination is being made.

(ii) “ Conversion Price ” means, as of any Conversion Date or other date of determination, $20.76, subject to adjustment as provided herein.

(c) Conversion Mechanics .

(i) To convert any Conversion Amount into shares of Common Stock on any date (a “ Conversion Date ”), the Holder shall transmit by facsimile (or otherwise deliver) a copy of an executed notice of conversion in the form attached hereto as Exhibit I (the “ Conversion Notice ”) to the Company in accordance with Section 19(a), with a copy to the Company’s transfer agent for the Common Stock (the “ Transfer Agent ”) and (B) if required by Section 14(d), surrender this Note to a common carrier for delivery to the Company as soon as practicable on or following such date (or an indemnification undertaking with respect to this Note in the case of its loss, theft or destruction). On or before the third (3rd) Business Day following the date of receipt of a Conversion Notice and, if required hereby, this Note (the “ Share Delivery Date ”), the Company shall:

(A) if the Transfer Agent is participating in The Depository Trust Company’s (“ DTC ”) Fast Automated Securities Transfer Program, credit such aggregate number of shares of Common Stock to which the Holder shall be entitled to the Holder’s or its designee’s balance account with DTC through its Deposits and Withdrawal at Custodian system; provided that such shares of Common Stock shall not be Restricted Securities; or

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(B) if the Transfer Agent is not participating in the DTC Fast Automated Securities Transfer Program or, if such shares of Common Stock are Restricted Securities, issue and deliver to the address as specified in the Conversion Notice, a certificate, registered in the name of the Holder or its designee, for the number of shares of Common Stock to which the Holder shall be entitled.

(ii) Pro Rata Conversion . Without limiting the remedies set forth above, in the event that the Company receives a Conversion Notice from more than one holder of Notes for the same Conversion Date and the Company can convert some, but not all, of such portions of the Notes submitted for conversion, the Company, subject to the restrictions in this Note, shall convert from each holder of Notes electing to have Notes converted on such date a pro rata amount of such holder’s portion of its Notes submitted for conversion based on the principal amount of Notes submitted for conversion on such date by such holder relative to the aggregate principal amount of all Notes submitted for conversion on such date. In the event of a dispute as to the number of shares of Common Stock issuable to the Holder in connection with a conversion of this Note, the Company shall issue to the Holder the number of shares of Common Stock not in dispute and resolve such dispute thereafter.

(iii) Limitations on Conversion . The Company shall not effect any conversion of this Note, and the Holder of this Note shall not have the right to convert any portion of this Note pursuant to Section 3(a), to the extent that after giving effect to such conversion, the Holder (together with the Holder’s Affiliates) would beneficially own in excess of 9.9% (the “ Maximum Percentage ”) of the number of shares of Common Stock outstanding immediately after giving effect to such conversion. For purposes of the foregoing sentence, the number of shares of Common Stock beneficially owned by the Holder and its Affiliates shall include the number of shares of Common Stock issuable upon conversion of this Note with respect to which the determination of such sentence is being made, but shall exclude the number of shares of Common Stock which would be issuable upon (A) conversion of the remaining, nonconverted portion of this Note beneficially owned by the Holder or any of its Affiliates and (B) exercise or conversion of the unexercised or nonconverted portion of any other securities of the Company (including, without limitation, any Other Notes or

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warrants) subject to a limitation on conversion or exercise analogous to the limitation contained herein beneficially owned by the Holder or any of its Affiliates. Except as set forth in the preceding sentence, for purposes of this Section 3(c)(iii), beneficial ownership shall be calculated in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended (the “ Exchange Act ”). For purposes of this Section 3(c)(iii), in determining the number of outstanding shares of Common Stock, the Holder may rely on the number of outstanding shares of Common Stock as reflected in (x) the Company’s most recent Form 10-K, Form 10-Q or Form 8-K, as the case may be, (y) a more recent public announcement by the Company or (z) any other recent notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. Upon the written request of the Holder, the Company shall within two (2) Business Days confirm orally and in writing to the Holder the number of shares of Common Stock then outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving effect to the conversion or exercise of securities of the Company, including this Note, by the Holder or its Affiliates since the date as of which such number of outstanding shares of Common Stock was reported. By written notice to the Company, the Holder may increase or decrease the Maximum Percentage to any percentage not in excess of 9.9% specified in such notice; provided that (i) any such increase will not be effective until the sixty-first (61 ^st ) day after such notice is delivered to the Company, and (ii) any such increase or decrease will apply only to the Holder and not to any other holder of Notes.

(iv) Principal Market Regulation . The Company shall not be obligated to issue any shares of Common Stock upon conversion of this Note if the issuance of such shares of Common Stock would exceed that number of shares of Common Stock which the Company may issue upon conversion or exercise, as applicable, of the Notes without breaching the Company’s obligations under the rules or regulations of the Principal Market.

4. Put Right .

(a) Put Right . If the Common Stock is suspended from trading or ceases to be listed on an Eligible Market for a period of five (5) consecutive Trading Days or for more than an aggregate of fifteen (15) Trading Days in any 365-day period (a “ Put Event ”), the Holder shall have the right, at the Holder’s option (the “ Put Option ”), to require the Company to repurchase for cash all or a portion of this Note at a purchase price equal to 100% of the outstanding Principal and accrued and unpaid Late Charges, if any, on this Note (the “ Put Price ”). For the avoidance of doubt, a Put Event shall be deemed to occur immediately prior to a Fundamental Transaction in which the Common Stock is converted into or exchanged for cash, securities or property, other than a Fundamental Transaction in which the Common Stock is converted into or exchanged for consideration at least 90% (by value) of which (excluding cash payments for fractional shares and pursuant to dissenters’ appraisal rights) consists of a Successor Entity’s common stock or equivalent equity security which trades or is listed or quoted on an Eligible Market.

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(b) Put Mechanics . In order to exercise a Put Option, the Holder shall (A) transmit by facsimile (or otherwise deliver) a written notice of the Holder’s election to exercise such Put Option (the “ Put Notice ”) to the Company in accordance with Section 19(a) and (B) if required by Section 14(d), surrender this Note to a common carrier for delivery to the Company as soon as practicable on or following such date (or an indemnification undertaking with respect to this Note in the case of its loss, theft or destruction). On or before the tenth (10th) Business Day following the date of receipt of a Put Notice and, if required hereby, this Note (the “ Share Delivery Date ”), the Company shall make payment of the Put Price in accordance with Section 19(b).

5. Rights Upon Event of Default .

(a) Event of Default . Each of the following events shall constitute an “ Event of Default ”:

(i) the Company’s failure to cure a Conversion Failure by delivery of the required number of shares of Common Stock within ten (10) Trading Days after the applicable Conversion Date;

(ii) the Company’s failure to pay to the Holder any amount of Principal or Late Charges when and as due under this Note (including in connection with any exercise of the Put Option);

(iii) the Company or any of its Significant Subsidiaries, pursuant to or within the meaning of Title 11, United States Code, or any similar federal, foreign or state law for the relief of debtors (collectively, “ Bankruptcy Law ”), (A) commences a voluntary case, (B) consents to the entry of an order for relief against it in an involuntary case, (C) consents to the appointment of a receiver, trustee, assignee, liquidator or similar official (a “ Custodian ”) for a material portion of its properties or (D) makes a general assignment for the benefit of its creditors;

(iv) a court of competent jurisdiction enters an order or decree under any Bankruptcy Law that (A) is for relief against the Company or any of its Significant Subsidiaries in an involuntary case, (B) appoints a Custodian of the Company or any of its Significant Subsidiaries for a material portion of its properties or (C) orders the liquidation of the Company or any of its Significant Subsidiaries, which order or decree, in the case of any of clauses (A) through (C), remains unstayed and in effect for 90 days or more;

(v) upon the later of (A) sixty (60) days after the occurrence of a default for failure to pay principal or interest on any other Indebtedness of the Company or any of its Significant Subsidiaries involving an outstanding principal amount in excess of $25,000,000, where such default would give rise to the acceleration of such indebtedness and (B) the actual acceleration of such other indebtedness; or

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(vi) a final judgment or judgments for the payment of money aggregating in excess of $25,000,000 are rendered against the Company or any of its Significant Subsidiaries and which judgments are not, within ninety (90) days after the entry thereof, bonded, discharged or stayed pending appeal, or are not discharged within ninety (90) days after the expiration of such stay.

(b) Remedies . Upon the occurrence of an Event of Default pursuant to Section 5(a)(iii) or 5(a)(iv), the outstanding Principal and accrued and unpaid Late Charges, if any, on this Note shall become immediately due and payable. If any Event of Default other than an Event of Default pursuant to Section 5(a)(iii) or 5(a)(iv) shall occur and be continuing, the holders of at least twenty-five percent (25%) in aggregate Principal amount of the Notes outstanding may, by written notice to the Company, declare the outstanding Principal and accrued and unpaid Late Charges, if any, on the Notes and the Other Notes immediately due and payable; provided that any declaration of acceleration pursuant to this sentence may be rescinded and annulled with the written consent of the holders of at least a majority in aggregate Principal amount of the Notes outstanding.

6. Adjustment of Conversion Price .

(a) Stock Dividends and Stock Splits . If the Company, at any time while this Note is outstanding: (i) pays a stock dividend or otherwise makes a distribution or distributions on shares of Common Stock, payable in shares of Common Stock or any securities of the Company or any of its Subsidiaries which would entitle the holder thereof to acquire at any time Common Stock, including, without limitation, any debt, preferred stock, rights, options, warrants or other instrument that is at any time convertible into or exercisable or exchangeable for, or otherwise entitles the holder thereof to receive, Common Stock; (ii) subdivides outstanding shares of Common Stock into a larger number of shares; (iii) combines (including by way of a reverse stock split) outstanding shares of Common Stock into a smaller number of shares; or (iv) issues, in the event of a reclassification of shares of the Common Stock, any shares of capital stock of the Company, then the Conversion Price shall be multiplied by a fraction of which the numerator shall be the number of shares of Common Stock (excluding any treasury shares of the Company) outstanding immediately prior to such event and of which the denominator shall be the number of shares of Common Stock outstanding immediately after such event. Any adjustment made pursuant to this Section shall become effective immediately after the distribution date of any such dividend or distribution and shall become effective immediately after the effective date in the case of a subdivision, combination or re-classification.

(b) Subsequent Rights Offerings . If the Company, at any time while this Note is outstanding, issues rights, options or warrants to all holders of Common Stock, such issuance will also be granted to the Holder on an as-converted basis without the Holder having to convert this Note in order to be entitled to such issuance.

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(c) Other Dividends . If the Company, at any time while this Note is outstanding, pays a dividend or otherwise makes a distribution or distributions of cash or other assets (other than any dividend or distribution described in Section 6(a) or 6(d)), such dividend will also be granted to the Holder on an as-converted basis (without regard to any conversion limitations) without the Holder having to convert this Note in order to be entitled to such issuance.

(d) Fundamental Transactions . If, at any time while this Note is outstanding, (i) the Company effects any merger or consolidation of the Company with or into another Person, (ii) the Company effects any sale of all or substantially all of its assets in one transaction or a series of related transactions to any Person other than a wholly owned Subsidiary, or (iii) the Company effects any reclassification of the Common Stock or any compulsory share exchange, in each case as a result of which the Common Stock is effectively converted into or exchanged for other securities, cash or property (in any such case, a “ Fundamental Transaction ”), then, upon any subsequent conversion of this Note, the Holder shall have the right to receive, for each share of Common Stock that would have been issuable upon conversion of this Note immediately prior to the occurrence of such Fundamental Transaction, the same kind and amount of securities, cash or property as it would have been entitled to receive upon the occurrence of such Fundamental Transaction if it had been, immediately prior to such Fundamental Transaction, the holder of one (1) share of Common Stock (the “ Alternate Consideration ”). If the Fundamental Transaction causes the Common Stock to be converted into the right to receive more than a single type of consideration (determined based in part upon any form of stockholder election), the Alternate Consideration into which the Notes will be convertible will be deemed to be the weighted average of the types and amounts of consideration received by the holders of Common Stock that affirmatively make such election. To the extent necessary to effectuate the foregoing provisions, any Successor Entity shall issue to the Holder a new Note consistent with the foregoing provisions and evidencing the Holder’s right to convert such Note into Alternate Consideration. The terms of any agreement pursuant to which a Fundamental Transaction is effected shall include terms requiring any such successor or surviving entity to comply with the provisions of this Section 6(d) and ensuring that this Note (or any such replacement security) will be similarly adjusted upon any subsequent transaction analogous to a Fundamental Transaction.

(e) Adjustment of Conversion Price upon Certain Self-Tenders . If the Company at any time or from time to time on or after the Issuance Date makes a payment of cash or other consideration to the holders of the Common Stock in respect of a tender offer or exchange offer, other than an odd-lot offer, and the value of the sum of (i) the aggregate cash and other consideration paid for such Common Stock, and (ii) any other consent or other fees paid to holders of Common Stock in respect of such tender offer or exchange offer expressed as an amount per share of Common Stock validly tendered or exchanged pursuant to such tender offer or exchange offer, exceeds the Volume Weighted Average Price of the Common Stock on the Trading Day immediately prior to the date any such tender offer or exchange offer is first publicly announced (the “ Tender Announcement Date ”), then the Conversion Price shall be adjusted in accordance with the following formula:

R’ = R x           O x P    

               F + (P x O’)

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For purposes of the foregoing formula:

R = the Conversion Price in effect at the expiration time of the tender offer or exchange offer that is the subject of this Section 6(e) (the “ Expiration Time ”);

R’ = the Conversion Price in effect immediately after the Expiration Time;

F = the fair market value (as determined by the Company’s Board of Directors in the exercise of their fiduciary duties with the concurrence of the Required Holders) of the aggregate value of all cash and any other consideration paid or payable for Common Stock validly tendered or exchanged (including any consent or other fees) and not withdrawn prior to the Expiration Time (the “ Purchased Shares ”);

O’ = the number of shares of Common Stock outstanding immediately after the Expiration Time, excluding any Purchased Shares;

O = the number of shares of Common Stock outstanding immediately after the Expiration Time, including any Purchased Shares; and

P = the Volume Weighted Average Price of the Common Stock on the Trading Day next succeeding the Tender Announcement Date.

Such decrease, if any, shall become effective immediately upon the opening of business on the day next succeeding the Expiration Time. In the event that the Company is obligated to purchase shares pursuant to any tender offer or exchange offer, but the Company is prevented by applicable law from effecting any such purchases or all such purchases are rescinded, the Conversion Price shall again be adjusted to the Conversion Price that would then be in effect if such tender or exchange offer had not been made. If the application of this Section 6(e) to any tender or exchange offer would result in an increase in the Conversion Price, no adjustment shall be made for such tender or exchange offer under this Section 6(e). The Company shall not effect any transaction described in this Section 6(e) if such transaction would have the effect of setting the Conversion Price at an amount that would cause the exercise in full of the conversion rights set forth in this Section 6 to result in a violation of NASD Rules or any listing standards applicable to the Company.

(f) Calculations . All calculations under this Section 6 shall be made to the nearest cent or the nearest 1/100th of a share, as the case may be. No adjustment shall be made to the Conversion Price unless such adjustment would require a change of at least 1% in the Conversion Price. Any adjustment that would otherwise be required to be made shall be carried forward and taken into account in any subsequent adjustment or in connection with any Conversion of the Notes. For purposes of this Section 6, the number of shares of Common Stock deemed to be i