Type: Supremely competent woman who fleetingly romances a show's leading man, sometimes with wisecracks (NCIS, Bones, Coupling), sometimes with a tragic backstory (24, Heroes). Also, her versatile piercing blue eyes can either be seductive or, as in her stint on Melrose Place, crazy.
Rep: Softer gets cast all the time because, "It's rare to find a great leading lady in her 30s who can do both comedy and drama and is as beautiful as she is funny," according to Hirschfeld.
Dissonance: How can she be anyone's love interest when she's really, as per her guest spot on The Ghost Whisperer, a ghost?
2 of 10
Garret Dillahunt, the Human Swiss Army Knife
Type: He can play creepy (a Terminator on The Sarah Connor Chronicles, a dangerous ex-husband on ER), holy (Jesus in The Book of Daniel), or comically doofus-y (A Minute With Stan Hooper, Fox's new fall sitcom, Raising Hope).
Rep: "He's equally convincing as a hick or a sophisticate. And he has a warmth to him," says Hirschfeld. He's even played two unrelated characters on single shows (Deadwood, CSI).
Dissonance: Even Jesus might not forgive his creepy pedophile on SVU.
3 of 10
Swoosie Kurtz, the Tough Lady of a Certain Age
Type: She can play a hardass judge (SVU), hardass mother (Rita Rocks), hardass spy (Chuck), or hardass with an eye patch (Pushing Daisies).
Rep: "It's a short list of attractive, strong women in their early 60s that have her kind of gravitas," says Hirschfeld.
Dissonance: There's no way Locke's crazy mom is also Blythe Danner's life partner (Nurse Jackie).
4 of 10
Gina Torres, the Slightly Supernatural Everywoman
Type: Torres specialized in grounded supernatural beings on fantasy fare like Xena, Hercules, and Angel, before graduating to playing grounded ordinary beings (Gossip Girl, 24, The Unit) and the occasional witch (The Vampire Diaries).
Rep: "She's feels like a real person," say Hirschfeld, but she works like a superhuman one. She's been on nine series in the past twelve months.
Dissonance: Her politically correct Gossip Girl mom would never fire a gun, as Torres has on, oh, every show she's appeared on.
5 of 10
Zeljko Ivanek, the Shady Authority Figure
Type: Whether Governor (Oz), Magister (True Blood), Homeland Security agent (Heroes), CIA Director (the forthcoming The Event), unrepentant creep (Big Love), or a sympathetic one (Damages), he always know a little too much.
Rep: "A great character actor, who can play a villain, a nemesis, or a boss," says Hirschfeld. Ivanek won the an Emmy for his 2008 turn on Damages. Plus, he does accents.
Dissonance: His skeazy Big Love polygamist would be arrested by his Heroes character.
6 of 10
Christopher Gorham, Nerdy Love Interest
Type: As an accountant on Ugly Betty, a not-so-popular kid on Popular, or a blind tech guy on Covert Affairs, Gorham is always the nice guy the girl is supposed to like when she figures out what's good for her. Even when he has superpowers, as on Jake 2.0, he's still a computer nerd.
Rep: Unlike many of the actors on this list, Gorham is more often cast as a leading man (Jake 2.0, Harper's Island) or primary love interest than in one-off guest roles. Still, none of his shows have quite stuck yet.
Dissonance: Ugly Betty's Henry really does not work for the CIA. (Or does he?)
7 of 10
Sonia Walger, Long-Suffering Lover
Type: Woman in a complicated, difficult relationship (Lost, FlashForward, Terminator: The Sarah Connor Chronicles, Tell Me You Love Me, Coupling, The Mind of the Married Man).
Rep: Walger appeared in comedies earlier in her career (the American Coupling, Mind of the Married Man), before transitioning to dramas, but even back then, she specialized in difficult relationships.
Dissonance: Penny would never touch a man who was not Desmond.
8 of 10
Alan Ruck, Just-Slightly-Off Guy
Type: He plays exactly who Cameron, his Ferris Bueller's Day Off role, would grow up to be: characters with chips on their shoulders who are always a little much — a little too neurotic, too enthusiastic, too rude, too misogynistic, or too creepy (Speed, Spin City, Greek, Persons Unknown).
Rep: Though he will forever be known as Ferris's best friend, Ruck works all the time, having appeared on ten shows in the past two years.
Dissonance: What dissonance? It's just sort of pleasantly surprising that Cameron grew up to be an actor.
9 of 10
Eddie McClintock, the Male Rena Sofer
Type: Though a bit less known than Rena Sofer, McClintock, like her, can do comedy (Better Off Ted, Big Day, A.U.S.A) and drama (Moonlight, CSI), and is often stuck playing the fleeting love interest (Bones).
Rep: McClintock looks and seems like a leading man, but up until his current role on Warehouse 13, he's never had a leading part.
Dissonance: The FBI agent McClintock played on Bones would never be questioned in a CSI panty-sniffing case.
10 of 10
Eric Balfour, Decent Dude With Menacing Vibe
Type: As on his new show, Haven, Balfour (who has been on too many quickly canceled shows to name) often plays someone you are supposed to be initially suspicious of. Sometimes he turns out to be a nice guy (24), sometimes not (Six Feet Under), and sometimes, as with The O.C., he turns out to be a nice guy before he turns out to be abusive.
Rep: Balfour's only 33, but he's been working steadily since he was 15, thus amassing an enormous number of credits on an enormous number of shows. Any show he's top-lined has failed, making him, next to Sofer, the most infamous show-killer on this list.
Dissonance: Too many instances to count.