He also appeared in other notable films, including: Coogan's Bluff (1968), The Last Tycoon (1976), Valentino (1977), Convoy (1978), Johnny Be Good (1988), Mobsters (1991), In the Soup (1992), Honeymoon in Vegas (1992), Indecent Proposal (1993), The Sleepy Time Gal (2001), Imaginary Crimes (1994), Beer League (2006), and Fort McCoy (2011).

Like Cassavetes, Wes Anderson frequently cast Cassel – first in Rushmore (1998), then in The Royal Tenenbaums (2001), and finally in The Life Aquatic with Steve Zissou (2004).

[2][3] His mother was remarried to a master sergeant in the U.S. Army Air Forces, and the family moved to Panama, where Cassel's stepfather was said to have won a nightclub in a game of craps.

He picked the military, and after three years of service and a brief stint in college, he returned to Detroit, where he built props for a theater company and took small acting roles.

He also appeared as "Cancelled", one of Colonel Gumm's henchmen in the 1960s Batman TV episode "A Piece of the Action", which also featured guest stars Van Williams and Bruce Lee as The Green Hornet and Kato, respectively.

Cassel had a small role in Steve Buscemi's directorial debut Trees Lounge and appeared in three films by Wes Anderson: Rushmore, The Royal Tenenbaums and The Life Aquatic.