Really, Archer's behavior toward just about any woman who has been unfortunate enough to cross his path could make the shortlist of the worst things he's ever done. But his treatment of his co-workers and friends, Pam Poovey (Amber Nash) and Cheryl Tunt (Judy Greer), feels especially worthy of a dishonorable mention.
Early in the series, Cheryl and Archer were known to occasionally hook up. Despite the fact that he was intimate with her on multiple occasions and also saw her every day at work, Archer couldn't remember Cheryl's name, and regularly called her Carol. He was also known to throw her clothing over his balcony in fits of rage and, as viewers saw in the very first episode of the series, force feed her ice cream, despite the fact that she's lactose intolerant.
Later in the series, he and Pam have their own twisted affair. While Archer enjoys hooking up with Pam, he doesn't want anyone to find out. To try and throw the others off his trail, he treats her cruelly when they are in public, often mocking and ridiculing her looks and personality. In the season 4 episode "Space Race Pt. 1," he even shoots Pam with a potentially deadly pulse rifle so that she won't reveal their secret relationship.
When it comes to the way Archer treats the people that are closest to him, however, nothing tops what he's done to poor Woodhouse (George Coe).