Heath Andrew Ledger (4 April 1979 – 22 January 2008) was an Australian television and film actor. After performing roles in Australian television and film during the 1990s, Ledger moved to the United States in 1998 to develop his film career. His work encompassed nineteen films, including 10 Things I Hate About You (1999), The Patriot (The Patriot (2000 film)) (2000), Monsters Ball (2001), A Knights Tale (2001), Brokeback Mountain (2005), and The Dark Knight (The Dark Knight (film)) (2008). In addition to his acting, he produced and directed music videos and aspired to be a film director.

For his portrayal of Ennis Del Mar in Brokeback Mountain, Ledger won the 2005 New York Film Critics Circle Award for Best Actor and the 2006 "Best Actor" award from the Australian Film Institute and was nominated for the 2005 Academy Award for Best Actor as well as the 2006 BAFTA Award for Best Actor in a Leading Role. Posthumously he shared the 2007 Independent Spirit Robert Altman Award (Independent Spirit Awards 2007#Robert Altman Award) with the rest of the ensemble cast, the director, and the casting director for the film, Im Not There, which was inspired by the life and songs of American singer-songwriter Bob Dylan. In the film, Ledger portrayed a fictional actor named Robbie Clark, one of six characters embodying aspects of Dylans life and persona. He was nominated and won awards for his portrayal of the Joker (Joker (comics)) in The Dark Knight, including the Academy Award for Best Supporting Actor, a Best Actor International Award at the 2008 Australian Film Institute Awards, for which he became the first actor to win an award posthumously, the 2008 Los Angeles Film Critics Association Award for Best Supporting Actor, the 2009 Golden Globe Award for Best Supporting Actor (Golden Globe Award for Best Supporting Actor - Motion Picture) and the 2009 BAFTA Award (British Academy Film Awards) for Best Supporting Actor.

He died at the age of 28, from an accidental "toxic combination of prescription drugs (Combined drug intoxication)." A few months before his death, Ledger had finished filming his penultimate performance, as the Joker in The Dark Knight, his death coming during editing of the film and casting a shadow over the subsequent promotion of the $180 million production. At the time of his death, on 22 January 2008, he had completed about half of his work performing the role of Tony in Terry Gilliams film The Imaginarium of Doctor Parnassus.