Brokeback Mountain's Heath Ledger and Michelle Williams have both joined the star-studded cast of I'm Not There, Todd Haynes' unconventional bio of Bob Dylan, says Production Weekly.

Ledger, who replaces Colin Farrell, will be one of a half-dozen prominent actors to play the iconic singer-songwriter in different stages of his life and various humors of his nature.

The others will be Cate Blanchett, Richard Gere, Christian Bale and Ben Wishaw (who is the lead in the upcoming adaptation of Perfume). One more actor to portray Dylan is yet to be cast. The film also stars Julianne Moore and Charlotte Gainsbourg.

The movie begins filming in Montreal this July. The soundtrack will include music from Jack White of The White Stripes, PJ Harvey and REM's Michael Stipe.