Godzilla and Iron Man are iconic (even archetypal) characters that have played a part in some great art. If you question my assessment of their significance, then just listen to the music they inspired.
Blue Oyster Cult's song about the big, radioactive lizard was never associated with the movies, but it was about the big, prehistoric lizard.
Blue Oyster Cult's Godzilla
Black Sabbath's Ozzy Osbourne started with the title, and then changed the story to avoid infringing on Marvel's copyright, but it's hard to imagine that he wasn't inspired by Tony Stark's alter ego. The song is so good that Marvel used instrumental passages from it to accompany one of the great movie endings of all time.
Black Sabbath's Iron Man
The Bad Plus is a jazz trio that did an absolutely raucous version of the song. The studio version of the song features pianist Ethan Iverson playing a detuned upright with one hand and a Steinway grand with the other. There is great energy in this song.
The Bad Plus' Iron Man
I know that Iron Man has Godzilla outnumbered two to one in this comparison, but hey: Godzilla is about 200 feet tall and has atomic fire breath. Iron Man is a geek from MIT with a bunch of shrapnel threatening his heart.