Cassel's early career was tied to fellow actor
John Cassavetes, who was informally part of his clan of actors. He made his film debut in the first film Cassavetes directed,
Shadows, on which he also served as associate producer. In 1961 he co-starred with Cassavetes in
Too Late Blues and 1962's
The Webster Boy. Cassel also appeared in
The Lloyd Bridges Show in the episode "A Pair of Boots", directed by his friend Cassavetes. Cassel appeared on such popular programs as ''
Twelve O'Clock High, Combat!, Voyage to the Bottom of the Sea, and The F.B.I.'' 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. In 1968, Cassel was nominated for the
Academy Award for Best Supporting Actor for his role as Chet in
John Cassavetes's
Faces. Other collaborations with Cassavetes included a starring role with
Gena Rowlands in
Minnie and Moskowitz, supporting roles in
The Killing of a Chinese Bookie and
Love Streams, and a cameo appearance in
Opening Night. Cassel appeared in many major Hollywood productions such as
Dick Tracy,
Tin Men, and
Indecent Proposal. He was also very supportive of the American
independent film community, especially in the wake of Cassavetes's death. 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. He had a featured role alongside
Jacqueline Bisset in
Christopher Münch's critically acclaimed low-budget drama
The Sleepy Time Gal. Cassel appeared for four seasons on comedian
Tracey Ullman's television series
Tracey Takes On.... ==Personal life==