It depends on what you have in mind, when it comes to "creating"...
Is it creating constructs? Then it's not a big deal and many characters are capable of doing such things. Especially the Lanterns with their hard light constructs.
Then you have someone like Atom Eve from the Image Comics (Invincible book), who does something similar like the Lanterns, but she actually changes the atoms of something or some crap like that, so what she does is to help out poor people in Africa, by creating food for them and so on. So she can create organic stuff.
If you have something like life creation in mind then that's pretty damn tricky, due to it being an insane feat, even for comic book standards.
Characters with reality warping and molecule manipulation should be capable of doing it, but they rarely ever do it. What about magic based characters like Dr. Strange and Zatanna? Are they creating? I would say no. They're rather summoning stuff like demons.
Does resurrecting someone fall into the creation category? You're giving someone life back after all.
Out of the top of my head the only instances of "creation" I have in mind is Molecule Man creating his own versions of the Beyonder, Dormammu, Mephisto and so on - in the same arc Sentry creating a tiny creature in his hand and ... didn't Dr. Manhattan create life later on, when he went to Mars?
Not even someone like Galactus can be considered as a creator, since he is actually only amping up characters with his power cosmic.
But yeah, the Beyonder and the Molecule Man should be the prime examples of such a feat.