He has appeared in the films Growing Up Brady (2000), The Good Student (2006), Puncture (2011), and Jobs (2013).

[2] In 1994, he made his theatre debut in a New York Off Broadway play titled Judy at the Stonewall Inn.

A few years later, he was cast in a play called Things You Shouldn't Say Past Midnight which he appeared on stage totally nude.

[1] Kassen has had small parts in television films and TV series such as Another World in 1994, Cybill in 1997,[1] and Third Watch 1999.

[3][4] In 2011, he appeared in the drama film Puncture, based on the true story of Michael David Weiss (played by Chris Evans), where Kassen played Weiss's law partner and best friend Paul Danziger.