Seymour Cassel was an American actor.

Cassel first came to prominence in the 1960s in the films of writer/director John Cassavetes. The first of these was Too Late Blues, followed by Faces, for which he was nominated for an Academy Award. Cassel went on to appear in Cassavetes's films Minnie and Moskowitz, The Killing of a Chinese Bookie, Opening Night, and Love Streams.

Cassel also appeared in actor Steve Buscemi's directorial debut Trees Lounge and appeared in three films by Wes Anderson: Rushmore, The Royal Tenenbaums and The Life Aquatic with Steve Zissou.

Among Cassel’s television credits: The Twilight Zone, Burke’s Law, Combat!, My Three Sons, The F.B.I., Batman, The Fugitive, Emergency!, Star Trek: The Next Generation, Matlock, Chicago Hope, Tracey Takes On…, Boston Public, Arli$$, and ER.

Cassel died April 7, 2019, in Los Angeles, California. He was 84.