<p>Heath Ledger was one the most charismatic and powerful screen presences of his generation. Having established a high-profile acting career by the age of 21 with the lead in 'A Knight's Tale', the young Australian went on to pursue a succession of increasingly diverse and often subversive roles that challenged the film industry's initial impression of him as a mere teen-idol. While a limited number of his early roles would hint at the greatness...