Kaitlin Olson is a nice person with a very dark sense of humor. Over the course of her career, first on It's Always Sunny in Philadelphia, where she's played the degenerate Dee Reynolds for going on 12 seasons, and now on The Mick, the upcoming Fox sitcom she executive produces and stars in, she's shown a willingness to throw out her vanity for the sake of a joke in a way that most actresses (and actors) would be afraid to do.

On The Mick, she plays Mackenzie "Mickey" Murphy, a trashy woman from Rhode Island who's forced to take care of her spoiled niece and nephews in ritzy Greenwich, Conn. when her sister and brother-in-law flee the country to avoid being arrested for white-collar crimes. Olson describes the show as a network sitcom with a cable sensibility, and Mickey pushes the boundaries of what a woman can do at 8:30 on a Tuesday night — for example, in one episode, she has to deal with a seven-year-old who's accidentally swallowed a balloon of heroin. Throughout it all, Olson shows her trademark disregard for looking cool or sexy or sane.

Watching Olson perform, it's hard not to wonder where her sense of humor comes from. So TVGuide.com asked her about some of the things that shaped her. And perhaps unsurprisingly, her biggest influences show a blend of darkness, goofiness and fearlessness.

These are five things that made Kaitlin Olson the comic force she is today.

Kaitlin Olson, <em>The Mick</em>Kaitlin Olson, The Mick

1. A head injury
When Olson was 12, she was in a terrible bike accident that left her with a fractured skull that required reconstructive surgery. She started junior high with a shaved head, and it didn't get easier from there. "It was the worst four years of my life," says Olson. She learned to be funny as a coping skill during these difficult years.

2. Her parents
Olson says that both of her parents are funny, but her dad in particular was the funniest person she knew when she was a kid. He would sing funny songs with fart noises. "He was just a goofball," she says. Her parents encouraged her to be funny, too. She remembers a bit she used to do as a kid where she would go kiss them goodnight and then steal something from their room. Each night she would take something bigger, so by the end she was carrying out a lamp from their bedside table while she wished them goodnight. Rather than telling her to knock it off, they went along with it. "They made me feel like like the funniest person in the world," she says.

3. Saturday Night Live
SNL was just as important to Olson as it is to any kid when they discover it, but it wasn't just the cast that was on when she was a teenager that made an impact; reruns of the early years were what really made her laugh. Gilda Radner in particular was a huge influence. "She was so fearless," Olson says. "She wasn't a woman who was trying to be to cute, she was trying to be funny."

4. Bad sitcoms
Lame sitcoms were just as influential for what not to do. She remembers even at a young age being annoyed by seeing the same thing over and over again in different forms — "like a wife going 'does this make my butt look fat?' and her husband going 'I'm not gonna touch that one!'" — which made her allergic to cliché. "I'm very attracted to comedy I don't see coming," she says.

5. Funny guys
Olson says, with a tinge of unhappiness, that she only had a few female comedy role models growing up because there were so few women allowed to be funny the way she likes at the time. So a lot of the comedians who made an impact on her are men like Bill Murray and Will Ferrell, guys who are willing to look stupid and go all out in pursuit of a laugh. "I like people who are ballsy and just go for it," she says.

The Mick premieres Sunday, Jan. 1 at 8/7c and moves to its regular time of Tuesdays at 8:30/7:30c starting Jan. 3 on Fox.