Christina Hendricks in 2012, at the Toronto International Film Festival in September. She was at the premiere of "Ginger & Rosa," a movie set in 1960s London and starring her and Elle Fanning. (Alberto E. Rodriguez / Getty Images) / SF

Hendricks pre-"Mad Men" fame, at the 2005 GLAAD Media Awards. She's been nominated for an Emmy for her work in "Mad Men." (Frederick M. Brown / Getty Images) / SF

Elisabeth Moss, 30, has been acting since she was a kid. As a teen, she was in "Picket Fences" and played Zoey Bartlet in "The West Wing." She's pictured in 2004 at New York Fashion Week. (Getty Images) / SF

Moss on Sept. 4, 2012, debuting a dramatic, blond pixie cut at the GQ Men of the Year Awards. Moss is also up for an Emmy, for best actress. (Ben Pruchnie / Getty Images) / SF

Before the hair cut, 2008. (Neilson Barnard / Getty Images) / SF

Post hair cut, at New York Fashion Week on Sept. 12, 2012. (Stephen Lovekin / 2012 Getty Images) / SF

Vincent Kartheiser, a 33-year-old screen actor since the 90s, first got widespread notice in "Angel," a spinoff of "Buffy the Vampire Slayer." He also did in the 2004 indie movie "Dandelion," for which he's pictured here. (Getty Images) / SF

Vincent Kartheiser in 2007. (David Livingston / Getty Images) / SF

Kartheiser looking more Pete Campbell-like at the Season 5 premiere of "Mad Men" on March 14, 2012. (Frazer Harrison / Getty Images) / SF

Jessica Paré, 29, grew up in Montreal and speaks French, which probably helped her "Zou Bisou Bisou" performance. She's pictured in 2004 at a Calvin Klein underwear party. (Getty Images) / SF

Paré appeared in a lot of Canadian productions, before making her Hollywood film debut in 2004's "Wicker Park." She's pictured at the movie's premiere. (Getty Images) / SF

Paré at the 2009 premiere of the movie "Suck." (C.J. LaFrance / Getty Images) / SF

Jessica Paré at last year's Emmys. (Kevin Winter / Getty Images) / SF

Paré goofing around with Jon Hamm at the 2011 Emmys. (Alberto E. Rodriguez / Getty Images) / SF

Before Jon Hamm, 41, became Don Draper, he was mostly known as the boyfriend of actress and screenwriter Jennifer Westfeldt. Here's the couple in 2003. (Getty Images) / SF

Jon Hamm in 2012, with January Jones, at a PaleyFest event for "Mad Men." Hamm is up for an best acting Emmy this year. (Jason Merritt / Getty Images) / SF

Jon Hamm before he was in "Mad Men," taking part in an animal-welfare fundraiser in 2005 with longtime girlfriend Jennifer Westfeldt. (Getty Images) / SF

Jon Hamm (R) is now so famous that he doesn't need his once better known girlfriend with him to garner attention. He's pictured on Sept. 6, 2012, at the Democratic National Convention in Charlotte, North Carolina. (Chip Somodevilla / Getty Images) / SF

Recognize this guy? It's Jared Harris in 2001, before he played the tragic Lane Pryce. His portrayal in "Mad Men" has snagged him his first Emmy nomination - for best supporting actor. (Getty Images) / SF

Jared Harris, 51, in 2012, at the Season 5 premiere of "Mad Men." (Frazer Harrison / Getty Images) / SF

Jared Harris, looking shaggy in 2003. A longtime film and TV actor, Harris was also in "Ocean's Twelve," "The Curious Case of Benjamin Button," and "The Last of the Mohicans." (Getty Images) / SF

Before January Jones, 34, started dating Josh Groban and playing Betty Draper, she dated Ashton Kutcher. They're pictured at the 2000 premiere of "Dude, Where's my Car?" (Getty Images) / SF

January Jones also hung out with people like Paris Hilton in her pre-"Mad Men" days. Photo from 2001. (Getty Images) / SF

And she didn't look like she had a stylist. Jones is pictured at an E! Online "Sizzlin' 16" party in 2002. (Getty Images) / SF

These days, January Jones often looks polished on the red carpet. She's pictured at a Schiaparelli And Prada event at the Met's Costume Institute Gala on May 7, 2012. (Larry Busacca / Getty Images) / SF

January Jones at the Season 5 premiere of "Mad Men." (Random trivia: Did you know Jones was in "Dirty Dancing: Havana Nights" in 2004?) (Frazer Harrison / Getty Images) / SF

Kiernan Shipka made her onscreen debut in "ER" at five months old, before appearing in many commercials and print ads. She's pictured in 2009 at the Screen Actors Guild Awards. (Jason Merritt / Getty Images) / SF

Kiernan Shipka, now 12, attends the Young Hollywood Awards on June 14, 2012. After appearing in shows like "Heroes" and "MADtv," she landed the role of Sally Draper when she was 6. (Valerie Macon / Getty Images) / SF

Kiernan Shipka at the Season 5 premiere of "Mad Men" on March 14, 2012. Her website says she's not yet allowed to watch the series. (Frazer Harrison / Getty Images) / SF

Peyton List, who plays Jane Sterling (Roger's wife) in 2005, at the premiere of Disney's "The Greatest Game Ever Played." (Getty Images) / SF

Peyton List (L) as Jane Sterling with John Slattery as Roger Sterling. Photo: AMC. / SF

John Slattery, 50, has made silver hair sexy for a long time. But back in 2006, he sported some darker locks for the screening of "Flags Of Our Fathers." (Getty Images) / SF

John Slattery in 2012, at the GQ Men of the Year Awards on Sept. 4. (Ben Pruchnie / Getty Images) / SF

Cara Buono (R), looking very different from Dr. Faye Miller, the character she played in "Mad Men's" Season 4 in 2010. Buono is pictured with Jill Hennessy for the premiere of "Two Ninas" in 2001. (Getty Images) / SF

Cara Buono, 41, at the 2011 Emmys, where she was nominated for an award for "outstanding guest actress in a drama series."
/ SF

Buono, who grew up in the Bronx and graduated from Columbia University, is pictured in 2003. (Getty Images) / SF

Dedicated "Mad Men" fans might recognize this actor. It's Randee Heller, 65, at a Golden Globes event on January 14, 2012. (Katy Winn / Getty Images) / SF

Randee Heller played the hilarious Ida Blankenship, Don Draper's former secretary. Heller also appeared in "The Karate Kid" and the movie's third sequel. Photo: AMC. / SF

Here's another actress who looks a lot different than her character. It's Alison Brie, 29, at the GQ Men of the Year Awards in September. (Ben Pruchnie / Getty Images) / SF

Alison Brie as Trudy Campbell, with Vincent Kartheiser as Pete Campbell. Photo: Ron Jaffe/AMC. / SF

Robert Morse, 81, was a Broadway actor and singer in his younger years, winning a 1962 Tony for his performance in "How to Succeed in Business without Really Trying." Morse is pictured in 2001 with daughter Allyn. (Getty Images) / SF

Robert Morse as the eccentric Bertram Cooper. Besides his vast Broadway career, Morse also played Dewey Hogg in "The Dukes of Hazzard." Photo: AMC.
/ SF

Michael Gladis ("Paul Kinsey") sports some serious bangs at the 2002 premiere of "K-19: The Widowmaker." (Getty Images) / SF

Michael Gladis, 35, on Sept. 12, 2012, at the opening night of "The Book Of Mormon" in Los Angeles. (Araya Diaz / 2012 Getty Images) / SF

"Mad Men" cast in 2007, at the International Press Academy Satellite Awards. (L-R): Christina Hendricks, Vincent Kartheiser, Elisabeth Moss and Aaron Staton. (VALERIE MACON / AFP/Getty Images) / SF

"Mad Men" cast in 2009, with Screen Actor Guild awards. From L-R: January Jones, Alison Brie, Kiernan Shipka, Elisabeth Moss and Christina Hendricks. (Jason Merritt / Getty Images) / SF

"Mad Men" cast in 2011, at the Emmys awards show. Will everyone's favorite 1960s drama win again? From L-R: Jessica Pare, Kiernan Shipka, Elisabeth Moss, Christina Hendricks, Cara Buono and Randee Heller. (Alberto E. Rodriguez / Getty Images) / SF