He was on the MTV show and in the three Jackass movies. Police tell news outlets in Pennsylvania that Dunn and a passenger died when the actor's Porsche went over a guardrail.
Jackass actor Ryan Dunn "was killed early Monday morning when his Porsche flew over a guardrail in West Goshen, Pa., slammed into a tree and burst into flames, according to local police," NBC Philadelphia reports. "Dunn's passenger — who hasn't been identified — was also killed."
As The Associated Press writes, "Dunn appeared on the MTV show that ran from 2000 to 2002 and its three big-screen adaptations. Most recently, he hosted Proving Ground on the G4 cable network."
He also appeared on NBC-TV's Minute To Win It.
If you're not familiar with the Jackass TV show and movies, as IMDB says the premise is this:
"Johnny Knoxville and his band of maniacs perform a variety of stunts and gross-out gags."