NEW YORK —  As Paris Hilton's sidekick on "The Simple Life," Nicole Richie showed a flair for comedy — and an impish glee at cracking jokes at others' expense.

The 26-year-old celebutante will again display a caustic streak in an upcoming guest spot on NBC's "Chuck," portraying the mean-spirited high school nemesis of undercover CIA agent Sarah Walker (Yvonne Strahovski).

In the episode, which will air this fall, Sarah must confront Richie's character when she is forced to attend her 10-year high school reunion for a mission with fellow agent Chuck Bartowski (Zachary Levi) as her date.

"Nicole auditioned for the part and was very funny," executive producer Josh Schwartz said in a statement Wednesday. "This role is a great opportunity for her to show off her comedic skills and be diabolically evil and kick some butt. It's going to be really fun."

She has previously guest starred on TV's "American Dreams" and "8 Simple Rules ... for Dating My Teenage Daughter."

Richie and her beau, Good Charlotte rocker Joel Madden, welcomed daughter Harlow Winter Kate Madden in January.