Jason Thirsk, American bass player (d. 1996)
Jason Matthew Thirsk (December 25, 1967 – July 29, 1996) was the bass player of the California punk rock band Pennywise from 1988 through his death in 1996. He grew up in Hermosa Beach, California.

Pennywise was formed in 1988 by Thirsk along with singer Jim Lindberg, guitarist Fletcher Dragge, and drummer Byron McMackin. Thirsk reportedly did not like to travel. Thirsk had been in rehabilitation for alcoholism and suffered from depression.