In my role playing career I have run many knock offs. I had a DM that let me run Darth Vader, Darth Maul, and a Wolverine knock off. Having Darth Maul knock on George Lucas front door was a fun RP session. Vader ended up in a uber fantasy (very high magic) setting where we even got some Stormtrooper golems and set up a Star Wars series of plays. (no movie screens) My Wolv knock off was named Badger and more or less a parallel uniberse. Of course Badger is not available in game and frankly claws regen suck in CoH anyways.
I also have some long running "just mine" creations. But I do enjoy taking a concept, like say Nosferatu, and try to experience what the world is like through that odd perspective. There has been so many stories told through human history that almost everything is inspired by or a amalgamation of other peoples ideas. Even my reptile man Sssautharg who was a Mana Fire/Evil Mentalist in RoleMaster was probably just bits of all my other RP adventures glued together. But not a knock off, nothing like him around I remember. But there is nothing truly new under the sun. Humans do not work that way.