O'Connor sure knows how to play a dad. He's been Trudy's father (and Pete's disapproving father-in-law) Tom Vogel on "Mad Men" since Season 1, but we just realized he also played Melissa Joan Hart's dad on Nickelodeon's "Clarissa Explains It All" back in the early '90s.
The halls of Sterling Cooper & Partners have been filled with a lot of familiar faces lately. Here are more than 20 "Mad Men" guest stars we recognize from previous roles in TV and movies. — Dave Nemetz, Yahoo! TV