Heath Ledger was one of the most charismatic actors of his generation. After establishing a high-profile Hollywood career at the age of 21 with the lead in A Knight's Tale, Ledger pursued a series of increasingly diverse, often subversive roles that belied his image as a teen idol. Edgier films such as Monster's Ball gave tantalizing hints of his talent, but it wasn't until Brokeback Mountain that he proved beyond question the...