Idris Elba
Although Idris Elba's character was truly terrible at his job, the actor still gave Detective Winn his all in the 2008 slasher flick Prom Night. The film wasn't Elba's debut, but it was his first time performing in a thriller aside from 28 Days Later. "I'm not too familiar with the prom world," Elba said. "Coming from England, we don't have prom." Hopefully, somebody let him know that murder isn't a quintessential part of American school dances.
Keira Knightley
The Hole (2001) marks Keira Knightley's first major role in a feature film. Knightley played Frankie, a teenager trapped inside of an abandoned underground nuclear fallout shelter with several of her peers. Knightley was a Hollywood newcomer at the time, described by director Nick Hamm as a younger version of Julie Christie.