If you take Mickey mouse for example and made a character that looked like him how much would different?

Question

would he have to be to not be infringing on the copyright of the owners of Mickey Mouse like Disney which owns the rights to him?

Answer 1

The laws regarding artistic infringement are not consistent. If a real case came to court the outcome would be tough to predict.

The words of the law say 30% change is necessary but how does anyone judge that in art?
In some cases parody and comedy have protected new artists from losing nasty law suits. But in those cases it was shown that the new artist did not stand to get monetary gain from the parody, otherwise it would have been infringement.
Recently artists have sued and won against companies and other artists on the grounds of infringing on style as well. Watch out!

In many cases in order for a company to keep it's copyright rights, they are required to sue, even if it against a small time artist.

Disney is well known for taking individuals to court to protect their artwork. In fact there lobbyists actually had copyright laws changed to protect Disney's creations from entering into public domain.

Answer 2

There is no line in the sand. If you could honestly swear in court that you never saw the likeness of MM, and when a client wanted a picture of a cartoon-like mouse, you drew this as an original creation, you would be free to go. However, if your actions were such that you knew you were stealing the Disney MM identity, or admitted to theft, then it wouldn't matter how much it was different.