Who is Leonardo DiCaprio ?

To prepare for the role, DiCaprio conducted extensive research and visited many of Hoover's haunts in Washington, D.C. "I do love playing historical figures simply because there's so much incredibly diverse, interesting information about a character when you can research their life," he explained to Backstage. "A lot of the stuff you'd never be able to make up as a writer."

In 2012, DiCaprio appeared as a slave owner in Quentin Tarantino's Western Django Unchained, co-starring Jamie Foxx, Kerry Washington and Christoph Waltz.

The following year, he re-teamed with Luhrmann to play one of literature's most intriguing characters, starring as Jay Gatsby in the adaptation of the F. Scott Fitzgerald classic The Great Gatsby.

DiCaprio again joined forces with Scorsese in the 2013 drama The Wolf of Wall Street, based on the memoir by Jordan Belfort, who gained notoriety for defrauding investors while lining his own pockets in the 1990s. DiCaprio's portrayal of Belfort earned him a Golden Globe for Best Actor, along with Academy Award nominations for Best Actor and Best Picture. Jonah Hill and Matthew McConaughey also starred in the film.

Wolf later sparked legal problems, with a former Belfort associate, Andrew Greene, claiming that the film's character based on him was "portrayed as a criminal, drug user, degenerate, depraved, and/or devoid of any morality or ethics.

He filed a lawsuit against the production companies associated with the feature, including Paramount Pictures, Red Granite Pictures, Scorsese's Sikelia Productions and DiCaprio's Appian Way Productions.

In late 2015, DiCaprio starred in The Revenant as Hugh Glass, an 1820s frontiersman forced to endure the wilderness after being left for dead. Directed by Alejandro González Iñárritu, the film was difficult to shoot due to frigid weather but immediately generated major awards buzz, earning a slew of Golden Globe nominations.

Upon winning for Best Actor, the popular DiCaprio received a standing ovation from his peers, and praised Iñárritu for his vision while also calling for support to indigenous communities and the protection of natural environments.

Making The Revenant was about man's relationship to the natural world.

A world that we collectively felt in 2015 as the hottest year in recorded history.

Climate change is real, it is happening right now," he said. "It is the most urgent threat facing our entire species, and we need to work collectively together and stop procrastinating.

We need to support leaders around the world who do not speak for the big polluters, but who speak for all of humanity, for the indigenous people of the world, for the billions and billions of underprivileged people out there who would be most affected by this.