Leonard King "Len" Lesser (December 3, 1922) is an American actor best known for his role as Uncle Leo on Seinfeld after having joined the cast during the second season. Len has appeared on American TV steadily since 1955 having appeared on scores of TV classics such as Alfred Hitchcock Presents, Get Smart, Quincy, The Rockford Files, Mad About You, All in the Family, Boy Meets World, Everybody Loves Raymond and, most recently, ER. He has also appeared in a variety of films such as Cool Hand Luke and The Outlaw Josey Wales. He also had a key role in the Clint Eastwood movie Kelly's Heroes. His tall stature and menacing profile, have earned him many roles as a hitman or criminal. Len has also had a recurring role on Everybody Loves Raymond as Garvin, a friend of Frank's who always lifted his arms in excitement whenever he saw Ray. In April 2007, Lesser began appearing in a commercial for Domino's Pizza as a man named "Wiseman" who chooses the Philly Cheese Steak pizza over his wife's choice, the Brooklyn Style pizza. Also, later that year he has appeared in a Stay in School commmercial for the AD council in a partnership with the US Army.

Is a Detroit Tigers fan.

Veteran film and TV heavy with hundreds of credits on his resume but didn't become became a semi-household name until his twilight years as Uncle Leo on TV's "Seinfeld" (1990).