So recently I read an issue or two of H'el on Earth where the main bad guy fools Supergirl into working for him of sorts. The two even kiss. To me this felt like bad writing but it got me thinking back on earlier versions, earlier stories with Supergirl. Kara Zor-El has always seemed to have a weakness for bad boys. Her dating history isn't that flattering. Here's what I remember/found out about Supergirl (version may vary) either dating and/or working with supervillains of some caliber:
1. Lex Luthor
2. Buzz, Demon of Chaos
4. Faux Kal-El
5. Owen Mercer a.k.a. Owen Harkness a.k.a. Captain Boomerang's son
SPECIAL MENTION: Comet the Super-Horse. Because the interaction was just so weird!
If there's more examples or you disagree with the list please let me know. I would just like to point out that I still like the character of Supergirl but wanted to illustrate something. Things like this do tip the scales and make me like characters like Power Girl a bit more though.