He is best known as the narrator in Woody Allen's Vicky Cristina Barcelona and his role as Peter Gregory in the first season of the HBO series Silicon Valley.
In 2005, he again appeared in Law & Order: Special Victims Unit, and also had roles in the films The Interpreter and War of the Worlds.
In 2012, he appeared in The Master, and Lincoln as Clerk of the House Edward McPherson, as well as a role in the television series Elementary.
[5][6] At the time of his death, he was filming his scenes as Peter Gregory in the HBO series Silicon Valley, having completed five episodes.
[3][9] On December 2, 2013, at the age of 48, Welch died due to complications of lung cancer at a hospital in Santa Monica, California.