From Dark Horizons:
http://www.darkhorizons.com/news08/080125g.php

Depp Replacing Ledger On "Parnassus"?

By Garth FranklinFriday, January 25th 2008 12:37am

Box-office megastar Johnny Depp, a friend of Heath Ledger, may take over a role left by the young Aussie actor who passed away earlier this week.

Ledger and Gilliam had been filming "The Imaginarium of Dr. Parnassus" in London since December and were scheduled to continue with interior and green screen shooting in Vancouver for another six weeks. When Ledger was found dead in New York on Tuesday, the project came to a screeching halt as the filmmakers struggled not only with their grief, but had to come to a decision as to where to go from there.

The question became whether to recast, shoot around or scrap the project altogether. Now it seems a whole other option is being considered - dual actors, same role. A studio source tells The Sun that "There is a point in the film when Heath falls through a magic mirror. He could change into another character after that and that is where Johnny would come in. It's a weird, fantasy, time-travel movie so Heath's character could easily change appearance. It would be a poignant moment. Johnny’s not working at the moment so everyone is praying he will do it."

The paper also says that Director Terry Gilliam has hand picked Depp for the role. The pair previously were going to work together on "The Man Who Killed Don Quixote", a project which famously collapsed due to all sorts of financial and environmental problems. Depp is currently involved with Michael Mann's crime drama "Public Enemies" alongside Christian Bale, while his two other projects "Shantaram" and "The Rum Diary" are put on hold because of the writers' strike.