36, ABC's Life on Mars Anyone who can steal scenes from Kyra Sedgwick—which the Irish-born actor did on The Closer—is leading-man material. O'Mara, who has one son with his wife, actress Paige Turco, wraps his stint as a time-traveling cop when the show ends April 1. But this role changed his life: "It put me on the map. I've been up-and-coming for 15 years."
30, FOX's Fringe The Australian actress shares one trait with her character, a kick-ass FBI agent: "I don't suffer fools, and Olivia doesn't either," she says. And while the job has its drawbacks—"More often than not, it's 4 a.m. and -40°," she says—there's been one big perk: She met her new husband, costar Mark Valley, on the set. "I fell madly in love. So it's been the best job of my career," she says.
36, HBO's The No. 1 Ladies' Detective Agency Gaining weight to play Alexander McCall Smith's beloved detective Mma. Precious Ramotswe? No problem: Scott learned she was pregnant with her first child (due in April) a day before heading to Botswana to film. Not so easy? "Working 14 hours a day in 115° heat," says Scott. "That was a challenge!"
29, A&E's The Beast Fimmel could tell that playing an FBI agent who learns the ropes from a possibly untrusty mentor (Patrick Swayze) would be special: "He's a tortured soul," says the Australian former model. "I knew it would be fun." Not to mention inspiring, given Swayze's battle with pancreatic cancer. "The most important lesson he taught me is to make the most of any opportunity," he says.