Maybe you like him best as the restless and complicated chain-smoker who commands a room with his brilliance and good looks, as he plays in "Mad Men."
Or maybe you prefer him as Kristen Wiig's jerky part-time boyfriend, Ted, from "Bridesmaids" -- rude and inappropriate in a soul-crushing way; one who would serve as a cautionary tale for women everywhere, if he wasn't already just an unfortunate reminder of who they dated in college.
For our purposes, however, we're going to simplify Jon Hamm in a way that he'd probably approve. A Midwestern native and about as normal of a guy as you're going to find among Hollywood types in the entertainment industry, Hamm is, at his core, a baseball fan.
And thanks to the soon-to-be-released "Million Dollar Arm," Hamm was able to meld his two passions together -- acting, in a movie about baseball.
Hamm has been everywhere lately in advance of "Million Dollar Arm" hitting the theaters on Friday. His whirlwind tour landed him in a suite at PNC Park in Pittsburgh, where he and MLB.com's Jeremy Brisiel officially launched the third season of "Express Written Consent."
Known for its casual banter and witty one-liners, "Express Written Consent" provides celebs a comfortable spot to take in a ballgame and talk about whatever comes their way.
Hamm's appearance took place during a Pirates-Cardinals game, which is all too appropriate considering Hamm, a St. Louis native, lives and breathes Cards baseball. And his new movie is about two pitching prospects from the Bucs' Minor League organization, who found their way to professional baseball by way of a reality show contest in their native India.
Hamm isn't a casual baseball fan -- he knows the game, loves the game and even plays the game in a men's league in California -- and can rattle off great moments in Cardinals history in a nanosecond. That covers all four-plus decades that he's been alive, whether those great moments happened recently, like Game 6 of the 2011 World Series, or 30 years ago, when his favorite player, Ozzie Smith, patrolled the infield.
"Since I was born," Hamm said, in response to how long he's rooted for the Cardinals.
In "Million Dollar Arm," Hamm plays sports agent J.B. Bernstein, who, while searching for the next big, undiscovered talent, stages a contest in India looking for the country's hardest thrower.
Among the contestants were Rinku Singh and Dinesh Patel, Olympic-caliber javelin throwers (although in the movie, they were depicted as cricket players) who won the contest, and $100,000 in prize money, and sign pro contracts with the Pirates.
The premise would sound absurd, if it wasn't actually true. The real Singh, who was in the booth with Hamm during the EWC taping, recalled his reaction when the whole process reached an unlikely peak.
"At first, I thought it was a joke," Singh said. "Who's going to give you a million dollars throwing this baseball? I really got serious when I qualified and when I got to Mumbai and did the final competition. All of a sudden, they gave me a $100,000 check. That made me flip out -- I was like, 'Really? That really happened?'"
For Hamm's part, the movie gave him a chance to see a part of the world he'd never been to, although he did admit he never imagined he'd be filming his first baseball movie in faraway India.
"Blast," he said, using a common baseball term during an EWC exercise titled "Three Up, Three Down."
"An absolute blast," he said. "I got to see a country I had never seen before, a continent I've never seen before. I had a wonderful time, saw so many sights that as a kid growing up in Missouri, I never thought I'd see. It was spectacular."
Though this taping of EWC was in conjunction with "Million Dollar Arm," let's be serious -- this is Jon Hamm, and "Mad Men" has been one of the most popular shows on television since its launch in 2007.
So there was no way we were going to go an entire taping without at least mentioning Don Draper, and maybe prodding Hamm -- just a little -- on where the dashing protagonist will ultimately land in life as the series inches toward its finale next spring.
Looking at a stack of common baseball phrases and asked to pick what most appropriately fits the end of Draper, Hamm grinned sheepishly and said, "I could really start a rumor." He quickly switched gears, though, and posted "Clutch" on the board.
"I think he's going to come clutch," Hamm said. "I think that's all I can say about that."
You sure about that?
"MVP," Hamm said, laying that card over Clutch. "Don is the MVP."
Hamm held up one last card.
"Lights Out, everyone."
Or, as they say in baseball -- wait 'til next year.
Alyson Footer is a national correspondent for MLB.com. Follow her on Twitter @alysonfooter.