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Captain Marvel (i.e. Billy Batson, "Shazam!") has long had a supporting character named Tawky Tawny, an anthropomorphic tiger. And Captain Marvel is now in the same universe as Superman.
The comic book series "Astro City" has a similar character, Loony Leo, but he is a lion not a tiger.
Just some suggestions to get you started.
Can't be either of those, as what I had in mind was definitely online, not printed
Okay, but your original description included "Superman" who is a character in printed comic books (and has been since 1938). If someone put Superman into a webcomic, couldn't they have put Tawky Tawny or Loony Leo into a webcomic?
Oooh, never thought of it that way.
Either way, neither of those seem to have helped
This involves a cartoony looking tiger, probably with no mouth and Spider-Man-esque eyes.