anime where the protagonist(s) is/are not exactly a good guy(s).

An antihero is basically a villain who is less evil because they hunt other villains. But sometimes the main character is just an a**hole.

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*Gokudo from Gokudo-Kun Manyuki: Utterly selfish to the core, doesn't learn his lesson in the end.

*Dejiko from DiGi Charat: Her rivals include the angelic sweetheart Piyoko & a ditzy popularity queen called Rabi~en~Rose. She treats her friends like crap & walks all over them. (The Panyo Panyo Dejiko is like a whole 'nother person).

*Lina Inverse from Slayers: Notorious for accidently destroying the very cities she was hired to protect, & to a lesser degree, blowing up restaurants. She murders bandits & steals from them.

*The Sanzo Party from Gensoumaden Saiyuki: A gambling, drinking, chain-smoking monk traveling with 3 demons, doing countless acts of genocide on a possessed race, & dooming any village they come in contact with.

*Ciel & Sebastian from Black Butler: Sebastian is a given, but Ciel is hardly an innocent child. A good chunk of the people his staff has killed died on his orders.