As I found myself worrying the niggling question of Charles Addams' pre-eminence in the annals of crossover-madness (a notion that would probably amuse Addams no end), I checked out a book to see if I could learn more about the first cartoon to introduce the Addams Family. The book, Stephen Cox's THE ADDAMS CHRONICLES, didn't reproduce the first cartoon with the Addamses but it did describe it thusly:
"[Addams'] pop masterpiece and longest-running characters were the Addams Family, who first say the dark of night 'around 1937' he recalls, in a cartoon of yet unnamed Morticia, Lurch, and visiting vacuum salesman (Lurch stated out with a beard)."
So that means that CA's first cartoon with his eponymous family was indeed a "monster mash," if, as I assume, both characters were drawn essentially as they've come to be known: as a slinky vampiress out of 1935's MARK OF THE VAMPIRE and a big (albeit bearded) galoot reminiscent of the Frankenstein Monster.
Although, now that I read about the beard, I wonder if there wasn't another monster-- one who normally sported a beard, and who actually may've had some experience "butling" before-- that might have been a more primary inspiration for proto-Lurch than the creation of Mary Shelley.
Someone like, oh, this guy:
This is "Morgan the butler," Boris Karloff's mute villain from THE OLD DARK HOUSE. I'm not sure just how much Karloff's casting in this role was affected by his tremendous popularity as the Monster in 1931's FRANKENSTEIN, but I seem to remember reading that once FRANKENSTEIN was a success, Universal Studios began trying to mold Karloff as a successor to the late (and very profitable) Lon Chaney, emphasizing horrific roles as a matter of course.
So which Karloff character was Addams referencing: Morgan or the Monster? I imagine that Lurch probably assumed his Frankensteinian qualities pretty early, for after all, the Monster certainly was a more iconic figure than the mute butler. Cox's book mentions that Karloff himself recognized the tribute CA had given him, for Karloff said in a foreword to a 1942 collection of Addams' cartoons: "I publicly thank Mr. Addams for immortalizing me in the person of the witch's butler."
Cox doesn't enlarge on the "witch" comment-- presumably Karloff's referring to Morticia-- but Cox does also make the same comparison between ADDAMS FAMILY and OLD DARK HOUSE that I made in my earlier essay HEROES AND HORRORS. Two minds thinking alike on devious subjects, and all that.
So, whether the first cartoon was in '37 or '38, it does seem that Charles Addams holds pride of place in the annals of monster mashery.