A new film explores the side of Heath Ledger we didn't see on screen.

For many, Heath Ledger was one of those ‘formative crushes’ you develop just before peak puberty, that explodes into a fully-blown obsession by the time you hit 15. From Ten Things I Hate About You to A Knight’s Tale, Heath was the center of many teen girl’s universes, right up until his sudden death.

It seems remarkable, then, for those fans to be the same age now as Heath was when he died in 2008.

At the time of his death, he was at the peak of his career, a father to newborn Matilda, and on the verge of major career accolades thanks to his role as the Joker in The Dark Knight. But due to an accidentally fatal combination of sleeping tablets and other prescription medication, Heath passed away in his New York apartment, alone. He was just 28.

Almost 10 years on, the actor’s incredible life is being revisited in a soon-to-be-released documentary titled I Am Heath Ledger. The film, created by Spike TV, delves into the private life of the star and his relationships with those around him.

A trailer released this week provides a glimpse into the larger-than-life character he was, as seen in private footage of Heath as well as interviews with his family and friends. One of the insights we get is his passion for directing and filming.

“He was always a director, acting was just a way to get there,” says childhood friend Trevor Dicarlo in the trailer, with ex-girlfriend Christina Cauchi adding, “There were always cameras around—a video camera, or a Polaroid camera, or a film camera. That’s the only way I think of him, with the camera in the hand.”

The footage of Heath as a young actor is harrowing - he was so full of life, so playful, and that smile? Oh man, that smile.

“Heath was the most alive human. And it wasn’t on the edge, it didn’t interest him,” remembers friend and musician Ben Harper. We see Heath in his incredible array of film roles, playing everything from a fresh-faced cowboy in Brokeback Mountain to the party-hard skater in Lords of Dogtown. He could do it all.

Fellow Australian actor Ben Mendelsohn points out his prolific range as an artist and an actor.

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“Before Brokeback Mountain came out, it would have been unthinkable to have a romantic tragedy involving two gay cowboys,” he says. “This is one of the biggest heartthrobs on earth taking on this character. That’s an artist.”

The trailer also features interviews with Brokeback Mountain director Ang Lee, the actor's sister Kate Ledger, and filmmaker Matt Amato.

Like all documentaries about talented people taken too soon, the trailer for I Am Heath Ledger is difficult to watch. He was so young, so healthy, so successful - and taken too soon. But for almost 10 years now there has been so much about the Aussie actor that we haven’t know. This film promises a look at the private world of Heath Ledger.

The film will air on Spike on May 17, 2017.

What's your favourite Heath Ledger performance?