Oscar-nominated actors Heath Ledger and Michelle Williams are joining the all-star cast of the Bob Dylan biopic "I'm Not There," written and directed by Todd Haynes.

Ledger, who replaces Colin Farrell, is in negotiations to be one of seven actors cast that will represent the different aspects of Dylan's life story and music. Williams will play Coco Rivington, a model with whom an androgynous folk star -- played by the already cast Cate Blanchett -- is taken. Also cast are Christian Bale, Julianne Moore and Richard Gere.

The movie represents an onscreen reunion for Ledger and Williams, who were Oscar-nominated for their performances in Ang Lee's "Brokeback Mountain."

Haynes and Killer Films principal Christine Vachon earlier had persuaded Dylan to assign the filmmakers the rights to his life story and music (HR 4/6/04). The first biographical screenplay about Dylan is set to go before the cameras in July in Montreal and was co-written by Haynes with Oren Moverman.

Vachon is producing with Dylan's business manager, Jeff Rosen. Wells and Goldwyn are exec producing.

Haynes has reteamed with cinematographer Ed Lachman ("Far From Heaven") and hired production designer Jan Roelfs ("World Trade Center") to create period looks for "I'm Not There."

Ledger is repped by CAA, and Williams is repped by Gersh. Lachman is repped by UTA, and Roelfs by Skouras.