Washington, D.C. 20549

                                   Form 13F

                              Form 13F COVER PAGE

Report for the Calendar Year or Quarter: June 30, 2003____

Check here if Amendment [_]; Amendment Number: ________

        This Amendment (Check only one.): [_] is a restatement.
                                          [_] adds new holdings entries.

Institutional Investment Manager Filing this Report:

                         Name:    Markel Corporation
                         Address: 4521 Highwoods Pkwy
                                  Glen Allen, VA 23060

Form 13F File Number: 28-6647____

The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

                        Name:  Thomas S. Gayner
                        Title: Chief Investment Officer
                        Phone: 804-527-3806

Signature, Place, and Date of Signing:

    Thomas S. Gayner             Richmond, VA                 08/08/03
-------------------------  -------------------------  -------------------------
       [Signature]               [City, State]                 [Date]

Report Type (Check only one.):

[_] 13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
    are reported in this report.)

[X] 13F NOTICE. (Check here if no holdings reported are in this report, and all
    holdings are reported by other reporting manager(s).)

[_] 13F COMBINATION REPORT. (Check here if a portion of the holdings for this
    reporting manager are reported in this report and a portion are reported by
    other reporting manager(s).)

List of Other Managers Reporting for this Manager:

        Form 13F File Number                    Name
        --------------------                    ----
              28-6056        Markel Gayner Asset Management Corporation