Nelson Van Alden
He started out on the "right" side of the law, as a Prohibition agent, but even before Nelson Van Alden went on the lam for drowning his partner, Agent Sebso (for the crime of being Jewish), he was always one of the series' most despicable characters. Whether he was pocketing the cash from liquor raids or neglecting his whiny baby mama Lucy Danziger, the deeply religious, sexually repressed Van Alden was just asking for a punch in the face. Once settled in Cicero, Illinois, with his new Norwegian wife and their children in Season Three, Van Alden seemed to be loosening up. And by Season Four, Van Alden had transitioned from unwitting errand boy for the Capones into a Walter White-esque gangster with a hard-on for bloodshed, big bucks and boning (Sigrid).