Not that he hasn't been involved in mainstream fare. He's had Hollywood roles in everything from Dick Tracy to Indecent Proposal, but it's the smaller films that he's received the most exposure like In the Soup with Steve Buscemi and the classic low budget masterpieces of John Cassavetes.
And it was through the Cassavetes films that Seymour Cassel has been able to soar, even getting an Oscar nomination in 1968 for the marital drama, Faces. Although he's considered a supporting actor, his best work was as an unconventional leading man in another John Cassavetes film, Minnie and Moskowitz, which is a one-of-a kind love story that is like no other ever made.
Talents like Seymour Cassel make movies richer, smarter and more fun for the viewer. His work, especially the ones from the Cassavetes era are well worth the effort to seek out and view. And after viewing, it's easy to understand why Seymour Cassel is Not Very Famous...but should be.