Cate Blanchett, Ledger's I'm Not There cast mate: "I deeply respect Heath's work and always admired his continuing development as an artist."

Dogtown director Catherine Hardwicke to People: "You could feel his heart and his soul... I think he was one of those rare people who could convey that on film... He was able to make you feel what he was feeling."

Brokeback director Ang Lee told the AP, "Working with Heath was one of the purest joys of my life... His death is heartbreaking."

Rachel McAdams, on her MySpace page: "He had undeniable talent and [was] a loving new father. It's so tragic to see it all end so soon and sudden."

Helena Christensen, to Page Six: "I was on my way over to pay him a visit when I found out. He was such a special and genuine person."

Geoffrey Rush, who costarred with Ledger in 'Candy': "I admired Heath enormously. He was such a sensitive and committed and daring actor."

"This is an unimaginable tragedy," I'm Not There director Todd Haynes tells Us Weekly. "Heath was a true artist, a deeply sensitive man, an explorer, gifted and wise beyond his years. There is no finer person on this earth."

John Travolta: "He is one of my favorite actors. His abilities are rare.... It's a tremendous loss."

Mel Gibson, a fellow Australian: "I had such great hope for him. He was just taking off and to lose his life at such a young age is a tragic loss."

"[Heath] was a courageous actor, and a great soul. He gave us the gift of sharing his fearless and beautiful love... for which all of us will be eternally grateful." - Brokeback Mountain producer James Schamus