“Mike & Molly” PLUS size laff-a-lot MELISSA McCARTHY is BIG and so is her incredibly expanding MONSTER EGO, say sources.

Melissa now  thinks she’s too big for TV – and insiders say she wants off of “Mike & Molly”!

Bolstered by her recent success on the big screen, the 42-year-old actress has become a “raging diva” on the set of the hit CBS sitcom.

“Melissa’s head has swollen to epic proportions,” revealed a Hollywood source. “She complains about the quality of scripts and grumbles about the direction the show is going in.

“She came back this season with a huge chip on her shoulder, and it’s creating a lot of tension and bad feelings on the set.”

Since her 2011 Emmy win for “Mike & Molly” and her hilarious turn in the blockbuster comedy “Bridesmaids” last year, Melissa’s career has exploded.

And after wrapping her latest film, “The Heat,” which co-stars Hollywood A-lister Sandra Bullock, returning to the daily grind of filming a TV show was apparently tough for her to swallow.

“She’s suddenly one of the hottest actresses in town and she’s been inundated with film scripts,” the source explained. “The sky’s the limit for her professionally, and she feels TV is holding her back from superstardom.

“It’s obvious she wants out of ‘Mike & Molly’ – now.”

But Melissa, who also stars in the upcoming “This Is 40” with Jason Segel and Megan Fox, is locked into the show for at least another year.

“She actually approached producers to see if she could get out of the contract or even buy her way out,” added the source. “But ‘Mike & Molly’ is a huge hit for the network, and they certainly aren’t going to let their biggest draw walk away from it.”