Jason Matthew Thirsk (December 25, 1967 – July 29, 1996) was an American musician who 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.
