Ken Osmond, 'Leave It to Beaver' star who played Eddie Haskell, dies at 76

Osmond, best known for his role as the troublemaker Eddie Haskell on the television comedy "Leave It to Beaver," died on Monday morning.

Ken Osmond, best known for his role at the troublemaker Eddie Haskell on the television comedy "Leave It to Beaver," died on Monday morning, his manager confirmed to NBC News. He was 76.

The cause of death is unknown.

Osmond, a native of Glendale, California, began his career as a child actor with his first speaking part at age 9 in the film "So Big," starring Jane Wyman and Sterling Hayden, followed by "Good Morning Miss Dove" and "Everything But the Truth." He also guest-starred on television series, including "Lassie," "The Adventures of Ozzie and Harriet," "Wagon Train," "Fury" and "The Loretta Young Show."

In 1957, Osmond auditioned for the Eddie Haskell role, which was originally intended to be a guest appearance, but those involved with the show were so impressed with Osmond's portrayal that the character became a key component of the series throughout its six-season run of 234 episodes.

Osmond portrayed Haskell as sycophantic to grown-ups while making fun of them behind their backs. He was a high school friend of Wally Cleaver, older brother of Theodore "The Beaver" Cleaver, and constantly trying to get his friends in activities that would get them into trouble. During the final years of the show, Osmond was in the U.S. Army Reserve.

When the series ended, Osmond continued to work as an actor, appearing on "Petticoat Junction," "The Munsters," and a return appearance on "Lassie." He was cast in the feature films "C'mon Let's Live a Little" and "With Six You Get Eggroll" but found himself typecast as "Eddie Haskell."

Osmond with Jerry Mathers, who played Theodore "The Beaver" CleaverWalt Disney Television via Getty Images

Osmond joined the Los Angeles Police Department in 1970 and grew a mustache to help secure his anonymity. In 1980, Osmond was struck by five bullets while in a foot chase with a suspected car thief and was protected from four of the bullets by his bullet-resistant vest, with the fifth bullet ricocheting off of his belt buckle. Osmond was placed on disability and eventually retired from the force in 1988.

Osmond filed a class-action lawsuit in 2007 against the Screen Actors Guild, asserting that SAG had overstepped its authority in collecting foreign royalties without disclosing the collection agreements until he and Jack Klugman threatened to file suit. The action was settled in 2010.

Sources tell Variety that Osmond passed away at his Los Angeles home surrounded by family members.

Osmond's son, Eric Osmond, released the following statement to NBC News: "He was an incredibly kind and wonderful father. He had his family gathered around him when he passed. He was loved and will be very missed."