David Lander, the actor known for playing Andrew "Squiggy" Squiggman on the popular ABC sitcom Laverne & Shirley, has died. He was 73.

Lander died Friday in Los Angeles from complications due to multiple sclerosis. The actor was diagnosed with the illness in 1984, but did not reveal it publicly until 1999. After going public, he toured widely on behalf of the National MS Society to promote treatment for the disease.

"Most people have no idea what MS is," the actor said in 2007. "One of the first things people asked me after I went public with my MS was 'Does this make you one of Jerry's kids?'"

Born David Landau in New York City in 1947, Lander planned from a young age to become an actor, studying at Manhattan's High School of Performing Arts, and later Carnegie Tech and New York University. At Carnegie, Lander met Michael McKean, who would become a longtime collaborator and his costar on Laverne & Shirley. It was here that they first created Lenny and Squiggy, the characters they would go on to play on the sitcom. After spending a year working on comedy projects rather than attending classes, the two were “not asked to come back,” as McKean told PEOPLE in 1978.

Lander moved to Los Angeles in 1968, briefly working with Rob Reiner as a TV writer before joining the comedy group the Credibility Gap along with McKean. The two were hired as writers on Laverne & Shirley in 1976, and wrote "considerably toned down" versions of Lenny and Squiggy into the first episode as the title characters' neighbors. Soon, Laverne & Shirley co-creator Lowell Ganz said in 2011, the writers "put them in every episode. We closed up their writers office, and they were part of the cast."

"Squiggy is a combination of people I knew and despised," Lander told PEOPLE at the height of the show's popularity. "You have more freedom playing people you hate. There are people like them who haven’t outgrown their silly dreams....Squiggy looks in the mirror and thinks he’s the handsomest guy in the world."

Lander's other credits included Steven Spielberg's 1941 and Robert Zemeckis' Used Cars, appearing alongside McKean in both, as well as voice work in Who Framed Roger Rabbit, A League of Their Own (directed by Laverne & Shirley's Penny Marshall), and The Iron Giant. On TV, he also appeared on Twin Peaks, The Bold and the Beautiful, and The Simpsons (as Squiggy), among many other shows.

Lander is survived by Kathy Fields, his wife of more than 40 years, and their daughter Natalie.

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This story originally appeared on: EW - Author:Tyler Aquilina