Watts, Gyllenhaal remember Heath Ledger on his 10th death anniversary

It is Heath Ledger's 10th death anniversary today and Hollywood stars such as Naomi Watts and Jake Gyllenhaal paid their heartfelt tributes to the actor.

"The Dark Knight" star was 28 when he died of cardiac arrest brought about by combined drug intoxication on January 22, 2008.

Watts, who dated Ledger from 2002 to 2004, shared a black-and-white picture of the actor on social media remembering him as a "true original" soul.

"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, humour and talent. I will never forget his gentle spirit," she wrote.

Ledger's friend, Gyllenhaal said the bond that he shared with his "Brokeback Mountain" co-star could not be put into "sound bite or can it in a three-minute interview".

"... Those who can do it I find sort of odd. I happen to not be one of those people. I think Heath meant a lot to a lot of people, the people who were fans and the people who saw his work and were moved by his work and the people who knew him as a person.

"He was just an incredible force and is still missed," he told E! News.

Actor Busy Phillips flew down to be with her friend actor Michelle Williams, Ledger's partner, on his death anniversary.

Phillips posted a selfie of her with her "Dawson's Creek" co-star.

She wrote, "It's ok", along with the picture that showed Williams with her eyes closed and leaning on her long-time confidant.

Ledger and "All The Money In The World" star were in a relationship for three years and parted ways one year before the actor's demise.

They have a daughter, Matilda, 12, together.