Kristen Wiig, so weird on ‘SNL,’ goes (somewhat) normal for ‘Bridesmaids’

Kristen Wiig has just come off an average Saturday night, one that required her to wear a 2-foot-high wig, shuffle lethargically around a stripper pole and bury her face in Helen Mirren’s cleavage.

“I was like, ‘Are you cool with this? ‘Cause I’m really gonna get in there,’” Wiig said of rehearsing the “magical bosom” scene with the 65-year-old British actress. “She was like, ‘Oh yeah. Do whatever you need to do and stay in there as long as you want.’ And I did. It’s pretty intense in there.”

Since joining the cast of “Saturday Night Live” in 2005, Wiig has emerged as one of the sketch comedy show’s most valuable players for her exuberantly weird characters, including the world’s most enthusiastic Target checkout lady, the freak sister in a family of Lawrence Welk singers and a bug-eyed Nancy Pelosi. Now, at 37, she is shedding the goofy costumes, accents and outlandish behavior to attempt that trickiest of parts — a real person. Wiig’s first leading big-screen role is in the May 13 release “Bridesmaids,” which she also co-wrote.

“All my characters are someone you don’t want to talk to at a party,” said Wiig, who off-stage is surprisingly introverted for a woman who makes her living wearing snaggle teeth and doll hands. “It’s always that person who’s being too loud, doesn’t have any social boundaries or says the wrong thing.”

In “Bridesmaids,” by contrast, Wiig plays a relatively normal, single thirtysomething woman whose life is thrown into disarray when she’s asked to be the maid of honor in her best friend’s wedding. “SNL” alumna Maya Rudolph is the agreeable bride, Rose Byrne of TV’s “Damages” an alpha bridesmaid, Melissa McCarthy of “Mike & Molly” the groom’s crude sister and “ Mad Men’s” Jon Hamm a gorgeous jerk.

Directed by “Freaks and Geeks” creator Paul Feig, “Bridesmaids” is the first female-driven film to come out of “The 40-Year-Old Virgin” and “Knocked Up” producer Judd Apatow’s mainstream comedy factory. And though the broad outlines of the script by Wiig and her writing partner Annie Mumolo fit comfortably in the white satin ghetto of the wedding genre, the execution is decidedly unladylike, with pratfalls, poop jokes and athletic sex.

“We wanted to write a comedy, not a female comedy, just a comedy that has a lot of women in it,” said Wiig in an interview at a hotel in her Soho neighborhood in New York. “There’s a difference.”

Added Mumolo: “We don’t want this to be some fluffy, frilly story.... We wanted it to be real.”

Reality often comes from the serious beats in “Bridesmaids,” as Wiig’s character, Annie, faces moments of loneliness and self-doubt. A pastry chef whose bakery has gone under, Annie crafts intricate cupcakes for no one, and moves back in with her mom in a state of financial and emotional defeat. She’s a woman, her nosy roommate observes, whose diary reads like “a very sad handwritten book.”

Wiig, a native of Rochester, N.Y., moved to Los Angeles after studying art at the University of Arizona and developed her comic sensibility in four years spent at the Groundlings, the L.A. improv troupe whose members have included Will Ferrell and Conan O’Brien. It was there that Wiig honed some of her now-famous characters, including befuddled film critic Aunt Linda, the giggling, chirping singer Björk and Target Lady, who is based on an actual clerk Wiig encountered at the discount chain’s Burbank store.

“When she’s in character, she’s really in it,” said Mumolo, who met Wiig at the Groundlings about eight years ago. “She’s riding it out. She’s enjoying being that character so much. You can hear her sort of muttering in Aunt Linda all day.”

In her 20s, Wiig paid her rent with odd jobs, including floral designing and acting in commercials — “Having to smile while holding a box of tampons wasn’t my dream,” she said. At one point she waited tables at the Universal Pictures commissary, where some of the studio chiefs who would eventually greenlight “Bridesmaids” regularly dined.

“A couple times I’ve seen executives and I’m like, ‘How do I know you?’” Wiig said. “Oh, I used to give you Cobb salad and Arnold Palmers, and I had a tie and khaki pants on.”

Wiig joined “SNL” just a few episodes after Bill Hader, with whom she shared a manager. “I heard there was this new girl coming in from Groundlings,” Hader said. “I thought, ‘I’ll help her out, show her around.’ I remember her first table read. I wrote this Vincent Price sketch and she proceeded to do a spot-on Judy Garland .... Immediately, it was like, oh … she’s better than all of us. She’s Michael Jordan. She’s gonna be running the place.”

Wiig’s focus helped her navigate “SNL’s” adrenalized culture, with its overnight writing sessions and competition for airtime among cast members. “The schedule was figured out in the ‘70s when everybody was on cocaine,” Hader said. “On writing night, most of us are hanging out. Kristen’s door is always closed and she’s in there working.”

Her first notable film role came in 2006 as a slutty mom in a little-seen film Feig directed called “Unaccompanied Minors,” but it was a small scene in “Knocked Up” in 2007 that won Wiig fans outside the “SNL” audience. As a passive-aggressive E! channel staffer, Wiig told Katherine Heigl’s character, “We don’t want you to lose weight, we just want you to be healthy, by eating less.”

“It was a part that didn’t really exist,” Apatow said. “I just knew I wanted two people to play folks at E!. I had never seen anybody stronger with nothing. She created this amazing character and tore down the house.” Apatow asked Wiig if she had any projects in the works, and she and Mumolo began working on the script that would become “Bridesmaids.”

Wiig would go on to provide some of the most memorable laughs in the films “MacGruber,” “Adventureland” and “Paul,” and play a rare straight-woman role in the roller derby movie “Whip It.” Between films and “SNL” seasons, she and Mumolo spent years honing their script.

Over time their friendship weathered the kind of potentially chasm-creating lifestyle changes the characters in “Bridesmaids” face — Wiig moved to New York and focused on her career, Mumolo stayed in L.A., got married and had two babies.

“We wanted to tell a friendship story and it really resonated with us,” Mumolo said. “Our relationship survived a lot. Things that could easily tear two people apart. This process could really cause trouble between two people. You have to make big decisions together. Big ones. You have to consider the other person.”

By the time they turned in their first draft, Wiig and Mumolo had carefully shaped Annie’s emotional arc but neglected their leading lady’s key asset, according to Apatow. “There were stages where I felt Kristen was writing herself as a straight person too much,” Apatow said. “She was very comfortable giving others the joke. I had to convince her to give herself the joke.”

Apatow and Feig added some of the movie’s trailer-friendly set pieces — a food poisoning breakout in a bridal shop and Annie’s pill-and-booze-addled meltdown on a plane.

When “Bridesmaids” began production in 2010, Feig and Apatow encouraged their cast — which includes many Groundlings veterans — to improvise. In an engagement party scene, Wiig’s and Byrne’s characters vie for status as the bride’s primary friend with increasingly antagonistic toasts. “We kept saying, ‘Do another toast, do another toast,’ all night long,” Apatow said. “Many of the great moments came from taking the handcuffs off of the women and seeing what else they could do.”

Apatow, whose oeuvre has largely been devoted to the extended phase of twenty- and thirtysomething male adolescence, said he sees little difference between “Bridesmaids” and his other films, besides all the skirts.

“We said, ‘We’re gonna make a great, funny movie that stars primarily women,’” Apatow said. “If it works, men will come too.”

Like her character in the film, Wiig is not married. But she has known her boyfriend, actor and producer Brian Petsos, since high school. “I relate to that ridiculous social pressure women have … that person we’re supposed to be in our 30s — married, kids, house, dog,” she said. “If we did have a message with the movie, we didn’t want people to think that you have to be married, because you don’t.”

Her next film role is as a mom in “Friends With Kids,” a movie written and directed by Hamm’s girlfriend, “Kissing Jessica Stein” co-writer and star Jennifer Westfeldt. Eventually, Wiig said, she’d like to transition to more dramatic roles and try directing, citing “Wendy and Lucy,” a contemplative drama starring Michelle Williams and directed by Kelly Reichardt, as an inspiration.

“A lot of comedians are big and broad and they hide their actual personalities,” Apatow said. “Kristen’s willing to expose her guts.”

In the meantime, Wiig is content to inhabit the ridiculous for 90 minutes every Saturday night.

“Once you have the costume and the wig, it’s easier to commit than not to,” she said. “Two minutes later you’re someone else, which is the best acting job you can have.”

rebecca.keegan@latimes.com