Mostel started his career as a boy Soprano at the Metropolitan Opera in New York. He graduated from Brandeis University. His Broadway debut was in 1971 with Unlikely Heroes. In 1973, Mostel had one of his most notable film performances as Herod in the Norman Jewison helmed Jesus Christ Superstar. In 1979, Mostel briefly starred in the television version of the film Animal House, Delta House, as "Blotto" Blutarsky, the brother of the character Bluto (played by John Belushi in the original film). He has since appeared in many films and Broadway productions.
On Broadway he appeared in the 1989 revival of The Threepenny Opera as Money Matthew, and as the frazzled head Writer in the original production of My Favorite Year, opposite Tim Curry and Evan Pappas.
