Since I only ever saw 3 episodes of Ultraman growing up I never knew about most of the monsters he fought during his series. Sure, the episode "Graveyard of Monsters" gave me some inkling, but the glimpses were so brief I only vaguely remembered them until I saw the episode again many years later. I did wonder what would happen if Ultraman and Godzilla ever faced off. Here you can see a version of it.
Don Glut wrote about this episode in one of his outstanding articles on Godzilla, and I sure did want to see it. It's one of the better episodes, though it can be hard to watch with older eyes, as Ultraman clearly toys with poor Kira/Jirass during the fight scene. It's mostly the deranged scientists fault the monster is destructive, but back then kids wanted to see the monster stopped, not saved. Oddly enough, the aforementioned episode does address this very topic.