Heath Ledger won an award posthumously .
Ledger received numerous posthumous accolades for his critically acclaimed performance in the film , including the Academy Award for Best Supporting Actor , a Best Actor International Award at the 2008 Australian Film Institute Awards -LRB- for which he became the first actor to win an award posthumously -RRB- , the 2008 Los Angeles Film Critics Association Award for Best Supporting Actor , the 2009 Golden Globe Award for Best Supporting Actor -- Motion Picture , and the 2009 BAFTA Award for Best Supporting Actor .