Saturday Night Live Movie

Most of the original SNL cast were members of Chicago’s Second City theater trope in the early 1970’s or its Toronto Canadian SCTV off-shoot that was sort of Canada’s SNL ( 1976-84) with John Candy being the most notable, arguably most successful alumni along with Eugene Levy, who starred in Schitt’s Creek and was the father of one of the main characters in American Pie movies. His son has turned out to be a damn good actor/comedian in his own right, too.
Eugene Levy.

Yes, I forgot to mention their time (most of them) with Second City. Good call.

EDIT: By the way, I would have to say ("I must say") that while actually many of them did well following its run, Martin Short has the longest success of any of the Second City TV cast and therefore probably beats out John Candy as the most notable of them.