Eustace the Monk (; c. 1170 – 24 August 1217), born
Eustace Busket, was a
mercenary and
pirate, in the tradition of
medieval outlaws. The birthplace of Eustace was not far from Boulogne. A 1243 document mentions a Guillaume le Moine, seigneur de Course, which indicates that the family lived in that vicinity.