The actress, who dated Ledger from 2002 to 2004, took to Instagram on Monday to pay tribute to the late actor, who tragically passed away on Jan. 22, 2008 at the age of 28.
Along with a photo of Ledger, Watts wrote to her Instagram followers, "Thinking about this beautiful soul today. 10 years ago he left this world. He was a true original. Heart always on his sleeve, with the most powerful charisma, strength, humor and talent. I will never forget his gentle spirit."