Actress Olivia Wilde is known as one of world's sexiest women. After her stint on the hit show House, she starred in such high-profile films as Cowboys and Aliens and In Time. In 2009, she came in at number one on Maxim's Hot 100 list. The Irish-American beauty (born Olivia Cockburn) and dedicated vegan was also named Sexiest Vegitarian by Peta in 2010. Her latest role in the highly anticipated Welcome to People movie shows that she has no intention of slowing down. Her blossoming career makes it hard to believe she's only 28-years-old today. Here are the actress' five hottest looks!