Diabolik/YMMV

Complete Monster: Federico the Duke of Vallenberg: to try and take over the Kingdom of Benglait he first created from nowhere the terrorist organization of the Grey Ravens to provoke a civil war, then married Altea and faked his death to avoid being identified as the leader of the Grey Ravens, then, after Benglait became a republic without him being able to take over, launched a series of terrorist attacks that nearly killed even Altea, and after that bit him back in the ass as Diabolik and Ginko dismantled a branch of his organization he launched other attacks, including a willingly failed one against Altea to justify both his faking his death and then his sudden return as motivated by his love for her and the desire to protect her while still trying to cause that civil war. Too bad for him that Altea saw through his final ruse thanks to her use of Fridge Logic and Diabolik managed to recognize him as the leader of the Grey Ravens who had him tortured many years earlier and was following Altea when she found the evidence of his guilt and him plotting...
Harsher in Hindsight: In the story Nel Tunnel della Pazzia (Inside the Tunnel Madness) Elizabeth Gay claimed her hate for Diabolik was born not from Diabolik's driving her to madness but by him choosing Eva as accomplice and partner instead of herself. Her words become much harsher after reading Nei Sotterranei di Clerville (Inside Clerville's Underground), that has a long flashback sequence of the times when Diabolik's true face was still unknown and Elizabeth his lover and Unwitting Pawn: the sequence shows that Diabolik did consider her as a possible future partner and actually tested her, with her proving her abilities but accidentally betraying his trust, prompting Diabolik to never use her help again.
Magnificent Bastard: Diabolik certainly (though some would argue that he's a Complete Monster), and Eva Kant has her moments.