I've seen him in a Wolverine special as well, but I can't remember which one. As for other appearances, I can't remember exactly when and where he's shown up, but I have seen him in other comics from time to time.
Those one shots are excellent! I'm really enjoying these, the best one so far has to be Fin Fang Four, with four classic monsters (lead by Foom himself) fighting another classic creature whose very name inspires sheer terror! (I'll leave you to guess who it is!
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