He's been found in his residence in New York.
UPDATE from Page Six:
January 22, 2008 -- Actor Heath Ledger was found dead today in a Broome Street apartment, apparently from a drug overdose.
Ledger was well known for his role in "Brokeback Mountain," and he stars in the upcoming "The Dark Knight" Batman movie as the Joker.
He split last year from wife, Michelle Williams, with whom he has a daughter.
His apartment was strewn with pills, sources said. It was unclear if it was an intentional or accidental death.Keep refreshing here and here for updates.