From PEOPLE Magazine Click to enlarge
The Melissa McCarthy who showed up to the Boston set of The Heat last summer with her two young daughters in tow could have passed for a friendly out-of-towner. Polite. Unassuming, even. "A sweet midwestern mom," as costar Michael McDonald puts it. But then the cameras starting rolling - and McCarthy morphed into a "beast," says castmate Bill Burr. The same woman who "doesn't even swear in real life," notes Heat director Paul Feig, "gets into character and suddenly the F-words start pouring out." And it's not just her verbal comedy that packs a punch. When the script called for her to hurl a phone book in one scene, "it came so hard that everyone thought my nose was broken," says McDonald. "Melissa ran over to see if I was all right. She is a much gentler person than you would ever know, given what she is known for on-camera."

Wildly uninhibited, profanely funny and unafraid to use "everything in her toolbox," as Feig puts it, to get a laugh, McCarthy now finds herself in that most exclusive of showbiz stratospheres: an Oscar-nominated, Emmy-winning superstar with a hit sitcom (CBS's Mike & Molly) and a big-screen summer smash (The Heat, costarring Sandra Bullock, which raked in $40 million during its opening weekend). After breaking out in 2011's Bridesmaids, McCarthy, 42, found that her success also made her Hollywood's reigning plus-size A-lister, a role she didn't audition for. "It's like if you're a painter and everybody focuses on how your hand looks while you're painting," says Feig. "'I'm painting these beautiful pictures; stop talking about my hand, you know? Talk about the painting.'"

But the topic of her weight can seem inescapable. A seemingly airbrushed poster for The Heat, in which McCarthy's figure appeared slimmed, sparked Internet debate. And New York Observer film critic Rex Reed branded her a "hippo" in a much-maligned review of her film Identity Thief in February. McCarthy told The New York Times that her first reaction to the piece had been, "Really? Why would someone okay that?" She also admitted that, had the review happened when she was 20, "it may have crushed me." She has spoken in the past about her struggles with dieting, though recently she has declined to say much at all about her weight, other than to tell More magazine, "I've been every size in the world. Part of my 20s, I was in great shape, but I didn't appreciate it. If I was a 6 or an 8, I thought, 'Why aren't I a 2 or 4?'"

What really matters, of course, is that she's hilarious. After her 2011 Emmy win for Mike & Molly, she earned an Oscar nod for Bridesmaids, then led Identity Thief to a surprise $34 million opening weekend earlier this year. Her supportive family keeps her grounded: Mom to daughters Vivian, 6, and Georgette, 3, with her husband, Ben Falcone, she skipped some press for The Heat to shoot Tammy, a passion project that she cowrote and Falcone is directing. "Especially with kids, you lose any sense of time or energy to worry about all the little stuff," she told More.

McCarthy loved putting on a show from an early age. Raised on a farm in Plainfield, Ill. - actress Jenny McCarthy is her cousin - "I'd perform for my poor mother in our laundry room. I'd make up songs that were never-ending," she told PEOPLE in 2011. After moving to Los Angeles, her comic instincts scored her a spot in the famed Groundlings improv comedy troupe, where she met Falcone, 39. "It started out really fun," she recently said of their romance. "It's no different now."

After stealing scenes on TV on Gilmore Girls and Samantha Who?, McCarthy got her big break on Mike & Molly. "Her physical comedy is so powerful," says costar Cleo King. "It puts you on the floor. Her timing is the best. She's got what she needs, so it should be no surprise that she is where she is." In Bridesmaids, "she was so inventive, so hilarious, so fast, so different," says Feig. "There is no vanity, no holding back." That's what McCarthy hopes sets her apart. "I feel like I've never gotten a job or taken [a role] because they needed a heavy person," she told PEOPLE last year. "I've gotten it because hopefully, and I think accurately, I was funny."

  • Contributors:
  • With Oliver Jones/Los Angeles,
  • Elizabeth Leonard/Los Angeles,
  • Paul Chi/New York City.