You can take Mickey from Steamboat Willie, make him wink, give him tie-dye shorts and pink skin, and use him as the logo Mickey Dishwasher Soap—you can't use him as is for a trademark because it's too generic.
You can't use his ears for an animation studio or a TV channel because it's easy to confuse with Disney's trademarks.
Trademarks are limited by category (which is why Apple Computer got into a lawsuit with Apple Records only after Apple Computer launched iTunes, before it was perfectly fair) and enforced on similarity. Also a trademark has to be distinct but doesn't have to be original, you can use a bitten apple as a trademark but you can't copyright that shape.
Edit: another difference between trademarks and copyright is that you never lose the copyright, but you must keep enforcing a trademark. If you let your brand become the generic term for a product, if you let others use your mark without suing them, then you lose the rights over the name.
You can take Mickey from Steamboat Willie, make him wink, give him tie-dye shorts and pink skin, and use him as the logo Mickey Dishwasher Soap—you can't use him as is for a trademark because it's too generic.
You can't use his ears for an animation studio or a TV channel because it's easy to confuse with Disney's trademarks.
Trademarks are limited by category (which is why Apple Computer got into a lawsuit with Apple Records only after Apple Computer launched iTunes, before it was perfectly fair) and enforced on similarity. Also a trademark has to be distinct but doesn't have to be original, you can use a bitten apple as a trademark but you can't copyright that shape.
Edit: another difference between trademarks and copyright is that you never lose the copyright, but you must keep enforcing a trademark. If you let your brand become the generic term for a product, if you let others use your mark without suing them, then you lose the rights over the name.