Keira Knightley prefers dark roles

London: Actress Keira Knightley says she prefers doing "darker" films.

The 27-year-old, who has shown the dark side of her personality in movies including ‘A Dangerous Method’ and ‘Anna Karenina’, admits she always wants to challenge herself as an actor and she chose role accordingly. "I try to do pieces that are as challenging to me as possible. Now one day that could be a romantic comedy or the Hollywood thriller that I`m currently doing (`Jack Ryan`), but lately they have taken a much more European, kind of a darker tilt," contactmusic.com quoted Knightley as saying. "But it`s been more about what I wanted to explore, the worlds I wanted to explore," she added. IANS