Kristen Stewart takes "Twilight" co-star Taylor Lautner to "American Ultra" premiere

Kristen Stewart was all smiles (yes, if you can believe it!) while at the "American Ultra" premiere Tuesday in Los Angeles.

It's no wonder, too. The actress brought her friend -- former "Twilight" co-star Taylor Lautner -- as her date to the premiere.

Stewart and Lautner's character were caught up with a love triangle throughout the "Twilight" series. But in real life, they're just besties.

Off of the set, Stewart dated another "Twilight" co-star, Robert Pattinson, for years. They both have since moved on. Stewart is currently linked to gal pal Alicia Cargile, while Pattinson is with singer FKA Twigs.

"American Ultra," which also stars Jesse Eisenberg, Topher Grace, Connie Britton and John Leguizamo, comes out on Friday. The movie follows a stoner (and a government agent), who is marked as a liability and targeted for extermination.