Bob Einstein, whose career as a comedy writer took a quirky turn into television acting as the hapless daredevil Super Dave Osborne, and later as a friend of Larry David’s on “Curb Your Enthusiasm,” died on Wednesday at his home in Indian Wells, Calif. He was 76.

His manager, Lee Kernis, said the cause was cancer.

Mr. Einstein played Marty Funkhouser, Mr. David’s pal and occasional antagonist, on “Curb Your Enthusiasm,” the long-running fictionalized version of Mr. David’s life on HBO. Mr. Einstein’s health precluded him from working on the series’ 10th season, which is now in production.

“Never have I seen an actor enjoy a role the way Bob did playing Marty Funkhouser on ‘Curb,’ ” Mr. David said in a statement. He added, “There was no one like him, as he told us again and again.”