I can't believe no one has mentioned Data and Lore from Star Trek: TNG. Classic evil twin story. BTW, Bart & Lisa's real evil twins are Lester & Eliza, seen in the episode where Itchy & Scratchy get taken off the air. [Comic Book Guy voice] Ha ha! I shall now take my rightful crown as king of all Simpsons knowledge. [/Comic Book Guy voice] Others: Samantha Carter/Evil replicant Samantha Carter (Stargate: SG1) Willow/Vampire Willow (Buffy TVS) Garth Brooks/Chris Gaines Will Smith/Robert Horry Gizmo/Spike (Gremlins)
I have an "Evil" Twin. It's a 70's era Fender Twin Reverb amp with and 135 Watt Ultra Linear power transformer.
I don't think that counts, Lester and Eliza just beat Bart and Lisa to the punch, so they aren't the exact opposite, which is what evil twins do. Bart's real evil twin is Hugo, though it was a Holloween ep so it's like alternate universe or whatever. Oh, and it turns out Bart was the evil one.
How bout this..evil twins, twins! The Olsen Twins and those freakin insane Olsen lookalike Neo-Nazi singer twins. As for Bender... that actually wasn't his twin but a friend who was another bending unit (so maybe I guess he was a twin brother). And he was the good one and Bender the bad. And the Urkel/Stephon relationship wasn't really a good/evil one..it was more of a geek/cool guy thing. And if Full House somehow made it to DVD why the hell hasn't Family Matters?! Homer I don't think had a twin, as his brother, Herb, I believe was younger than him.