One of the perennial debates in comics is the question, "Who created (insert character here)?" You really have to put "(insert character here)" into the end of that question, because there are debates over who came up with Spider-Man, who created Cable, whose idea was Venom...really, any successful and popular character you'd care to name, there's probably going to be a few extra people claiming that it was really their idea. (In general, this only happens with successful and popular characters. To quote Peter David, "Nobody argues about who created Night Nurse.")
The debate doesn't just encompass comics fans and historians, it actually goes all the way up to the creators themselves. Plain and simple, there's a lot of money to be had if you can prove that a character is your intellectual property and you weren't properly compensated for that idea, and so there's a strong monetary incentive to claim creator's rights. This doesn't mean that (to choose a random example) Steve Ditko is lying, or just in it for the money when he claims he created Spider-Man...I'm sure he honestly feels that his creative contributions to the concept are being overlooked, and deserve to be acknowledged. (Obviously, I haven't talked to him personally.) But the money issue will always be there, and deserves to be mentioned. Many lawsuits over copyright and trademark in the comics industry resemble all the worst parts of a custody battle and a contract dispute put together.
And that's fine, when it goes to court. The law has decided that the originator of a concept deserves to be compensated for their idea if money is to be made off of it, and if lawyers want to sift through all of the competing recollections and ambiguous evidence and try to say, "So-and-so created Character X", they can have fun with it. But we, as comics fans, aren't arguing for the benefit of a court of law. It's time for us to get past that question of "Who created?", and acknowledge that as a practical matter, it's actually a meaningless question.
It's meaningless because the creation of a character is actually just the first step in a long, long process of development that will see the character pass through multiple hands, writers and artists and editors (and in some cases actors and screenwriters and directors) all adding new elements as they interpret that initial concept in a different way. Ultimately, the interpretation that becomes popular might have nothing to do with that initial concept beyond simply the name. Arguing about "the creator" misses the point; it's all about the most important influences, not the first.
For example, there's really no question that Len Wein created Wolverine. He wrote the character into an issue of the Hulk, and then when he was coming up with the "All-New, All-Different" X-Men with Dave Cockrum, he decided to toss the character in to represent Canada in their international team. Len Wein = creator of Wolverine. Very simple.
Except that Wein intended Wolverine to be an actual wolverine, mutated by the High Evolutionary into a human form. He was going to be a teenage punk, a rough-and-tumble scrapper who had trouble getting along with human beings because of his animal ancestry, and who used metal blades built into his gloves to compensate for the natural claws that the High Evolutionary took away. (Edit: Len Wein personally swears that this is not what he intended for the character; Wolverine was meant to be a teenage punk with metal blades built into his gloves, but the High Evolutionary was not involved, nor were any actual mustelids. There was an intended plan to make Wolverine a mutated animal, but Len Wein was not, I repeat, not involved in it.)
Now, there's no question in my mind that this is a good concept for a comics character--one only needs to look at the Teenage Mutant Ninja Turtles to see how it could become a commercial hit. But Dave Cockrum first drew Wolverine without the mask, and he made him look to be in his forties instead of his teens. Chris Claremont took over the book shortly after its rebirth, and he promptly ditched the "mutated wolverine" idea in favor of his being human. John Byrne came on as artist not long after that, and spent a lot of time and energy suggesting ideas for Wolverine because he liked the idea of a Canadian super-hero. By the time the Claremont/Byrne era ended, Wolverine had a different origin, a different personality, a different set of powers, and a different costume. The only thing you can point to that stayed the same was the name, and even then, Claremont and Byrne gave him the "Logan" sobriquet. While there's still no question that Len Wein created Wolverine, calling it "his" character creates a serious misperception in the mind of the average fan. (It would be very interesting to visit an alternate reality where he'd stayed on the book, though, wouldn't it?)
Another, simpler example: Stan Lee and Jack Kirby created the Hulk. But the character they wrote and drew in "Hulk #1" wasn't dumb, wasn't green, didn't change when he got mad, and didn't have the distinctive "Hulk smash puny humans!" dialogue that generations of comics fans know and love (or hate, in the case of Marvel's current editorial staff and just about every writer they put on the book.) Those elements were added over months and years, frequently by other writers and artists. Even then, you could make a solid case that the interpretation that's stuck most solidly in popular culture is Lou Ferrigno's wordless, wild-haired Hulk. Should Lou Ferrigno be credited as "the creator of the Hulk"? Of course not. But his performance and what it brought to the concept shouldn't be brushed aside simply because he wasn't first in line.
Sometimes, of course, the creator and the prominent influence are one and the same. The Fantastic Four always seem to curve back towards the version that Stan Lee and Jack Kirby created in their classic 102-issue run on the series. But in general, it's worthwhile to talk about all the talented people who worked on making a popular character who they are today, and leave the discussions of who created them to the courts. Because while it might seem like a custody dispute sometimes, and while we use it as an analogy a lot, these are not the children of their creators. There is nothing inherent that they give to the characters that cannot be removed by a later writer or artist, no hereditary stamp that is preserved forever. A new creator can always transform the concept so completely that it may as well be theirs. Because biology may be destiny, but fictional characters don't have genes.