He won an `` Outstanding Guest Actor '' Emmy in 2001 for a part on The Practice , but is currently most famous for playing Zep Hindle in the 2004 film Saw and Ben Linus in the television series Lost . In 2001 , he won an Emmy Award as `` Outstanding Guest Actor in a Drama Series '' , for playing the ( fictional ) confessed serial killer William Hinks in several episodes of The Practice . One of Emerson 's best known works was in 2004 as the character Zep Hindle in the horror movie Saw .