Nicole Richie is... a gun-toting action villain?

The 29-year-old former Simple Life star makes a guest appearance in US spy drama Chuck as Heather Chandler – the high-school nemesis of female lead Sarah Walker, played by Yvonne Strahovski.

In the sneak peek for the upcoming episode – set to be aired next Monday - mum-of-two Richie is seen fighting with Sarah and wielding a huge automatic machine gun.

“I box three times a week and I really believe that it helped,” Richie said of her preparation for the role.

“But I’ve never gone to a shooting range – that gun was bigger than me!”

Nicole, the daughter of singer Lionel Richie, shot to fame as the sidekick of childhood pal Paris Hilton in the reality show The Simple Life.

But the former wild child has managed to stay clear of trouble since becoming the mother of two children – two-year-old daughter Harlow and one-year-old son Sparrow - with rocker boyfriend Joel Madden.

Richie – who has also penned two books – has denied reports that she will be tying the knot with the singer by the end of this year.

“Joel and I are not big planners, we just kind of go with the flow of things,” she said.