"I think when I received the script, attached to it was this kind of — these fears and anxieties that have been kind of manufactured over time from other people in the industry," he said during an interview last December on The Early Show. "But after reading the script, they all just kind of disappeared and it was reduced down to a lump in my throat."
Also starring in the film are Jake Gyllenhaal and Michelle Williams, Ledger's significant other and the mother of his baby daughter. Gyllenhaal and Williams also are up for Oscars for their supporting roles.
More from CBSNews.com on Heath Ledger and on the Oscars...
Ledger was born and reared in Australia, where he got his start on television. For instance, in 1996, he played Snowy Bowles, a gay bicyclist, in a TV series called "Sweat." The following year, he played a Celtic warrior prince in a summer series called "Roar."
On the silver screen, he got a big break when he played Patrick Verona in "10 Things I Hate About You" in 1999. Then he landed the part of Mel Gibson's son in "The Patriot" (2000) and Billy Bob Thornton's son in "Monster's Ball" (2001). That same year, he played a medieval swashbuckler in "A Knight's Tale."
Ledger took parts in a few movies that did not have much commercial success, including "The Order" (2003) and "Ned Kelly" (2004). Besides "Brokeback Mountain," he starred in another 2005 movie: "Casanova," in which he plays the title role.
He also played the field before he met Williams; his girlfriends included actresses Heather Graham and Naomi Watts.
Williams and Ledger named their baby girl Matilda. Ledger himself was christened Heathcliff in honor of the tortured hero of "Wuthering Heights." One of his sisters is named Catherine after the book's heroine.