Here's an unusual animated special that the folks at Rankin-Bass produced in 1970 — or at least it aired in April of that year. It was called The Mad, Mad, Mad Comedians and I believe it was intended as the pilot for a series. The idea was that each week, the antics of a bevy of great funnymen and women — some from the past, some from the present — would be animated. This was the only episode produced and it featured Jack Benny, George Burns, Phyllis Diller, Flip Wilson, The Smothers Brothers, Henny Youngman, W.C. Fields, George Jessel, Jack E. Leonard and the Marx Brothers. Most of the voices were done for this show by the comedians themselves, though the Flip Wilson and Smothers Brothers material is from those gents' records.
The most interesting segment is probably the one with the Marx Brothers for which Groucho recorded his own voice. Paul Frees, who's also heard as the announcer throughout, did the voices of Chico and Zeppo with Joan Gardner as the Empress, and the script is adapted from I'll Say She Is, the first show the brothers did on Broadway. Later on, Mr. Frees impersonated W.C. Fields for a segment that used a chunk of one of Fields's classic routines.
The caricatures of all these folks were done by Bruce Stark, who was a sports cartoonist for a couple of decades for the New York Daily News and later branched out into drawing for all the major magazines, including MAD. His work was seen a lot in TV Guide back when everyone read TV Guide, as opposed to now when no one reads TV Guide. Likenesses aren't easy and it's particularly difficult to do them in a style simple enough for animation. I'd say Mr. Stark did a great job. What I suspect caused this to remain unsold as a pilot was the disjointed nature of the program…and the frequent repetition of the annoying theme didn't help. But see what you think.
This video is in two parts which should play one after the other in the player I've embedded below. The Marx segment starts around 11:10 into the first part and continues into the second…