Fackler in the comedy films Police Academy, and as Rabbi Glickman[a] on the sitcom Seinfeld.
In 1980, he appeared on Fridays, an early 1980s ABC sketch show modeled after NBC's Saturday Night Live, where most of his appearances showcased his musical talent and radio DJ-style voice, most notably in the recurring sketches "The Latin DJ" and the one-off sketches "KPLO" (about Palestine Liberation Organization terrorists hosting a radio show in their bunker) and "A Classical Get-Down" (about a classical pianist who hosts his radio show like a Top 40 station).
In the 1990s, Mahler appeared on the television series The Famous Teddy Z and had a recurring role on Seinfeld.
He had minor roles in the movies Hook, Dick Tracy and Loaded Weapon 1.
From 1995 to 1998, he starred as a rabbi whom Elaine befriends in the Seinfeld episodes "The Postponement", "The Hot Tub" (scene deleted), "The Serenity Now" and "The Finale".