I’m having a hard time thinking of funny people who stayed funny, or better yet, got funnier, late in their careers.
I happened to be thinking of comedians like Bill Cosby and George Carlin who had long, successful careers; yet their best, really classic material, all came in the early-to-middle parts of those careers. Opinions differ on whether their later stuff is still funny, but hardly anybody claims that it’s as funny as they used to be.
Of all the comedians, comedy writers, comic actors, etc. I can think of who have really made me laugh, and who have been around a long time, some of them got stale, some of them mellowed, some of them just kept repeating themselves, and some of them branched out and did quality work outside the realm of pure comedy. But I’m having a hard time thinking of anyone who stayed fresh and laugh-out-loud funny well into middle or old age; so that if they had died at age, say, 50, the world of comedy specifically would have missed out on something special.