With Bridesmaids, The Heat and Tammy, Melissa McCarthy has already established herself as one of the finest comedy actresses on the planet though in Paul Feig's latest movie Spy, the 44-year-old from Illinois has arguably cemented herself as the finest comedy actress on the planet.

SpyMelissa McCarthy is secret agent Susan Cooper in Paul Feig's Spy

In it, she stars as Susan Cooper, an unassuming CIA analyst and unsung hero behind the Agency's most dangerous mission. However, when her partner (Jude Law) falls off the grid, she volunteers to go deep undercover to infiltrate a world of deadly arms dealers and prevent a global disaster. The critics are uproarious.

"[It made] the audience howl so loudly that it was hard to hear some of the lines," said Alex Needham of The Guardian.

"Melissa McCarthy comes into her own as a comic star in Spy, stepping out from recent supporting- and co-headlining roles to become the big screen A-lister she promised to be in 2011's Bridesmaids," said John DeFore of the Hollywood Reporter.

Melissa McCarthyRose Byrne co-stars in Spy

"Melissa McCarthy gets the funniest, most versatile and sustained comic showcase of her movie career in this deliriously entertaining action-comedy," wrote Justin Chang of Variety.

"It's a back-handed compliment, sure, but Spy is easily Melissa McCarthy's best movie yet," wrote Jim Schembri of 3AM.

Spy, out next weekend, is almost assured of commercial success though it's the critical reaction that gives a major boost to the all-female Ghostbusters movie, which Feig is directing and which McCarthy is the lead star. 

Watch the trailer for Spy: