Mark Simpson, known by the pen name Jock, is a Scottish cartoonist, best known for his work in 2000 AD, The Losers, and more recently Batman and Wolverine. He is also known for Wytches by Image Comics.

The Losers is a comic book series written by Andy Diggle and illustrated by Jock, and published by the Vertigo imprint of DC Comics. It ran for 32 issues from August 2003 to March 2006.