Heath Ledger
From Internet Movie Firearms Database - Guns in Movies, TV and Video Games

Heath Ledger with a converted Glock 17 as The Joker in The Dark Knight
Heath Ledger was an Australian actor best known for his Academy Award-winning portrayal of the Joker in The Dark Knight. He passed away in 2008 from an acute drug intoxication at the age of 28.
Heath Ledger can be seen using the following weapons in the following films: