He also played a Secret Service agent in In the Line of Fire and an ex-FBI agent in Bloodwork.
Even in 2008's Gran Torino, his character was reminiscent of Dirty Harry. So it might be understandable that Eastwood would delve into the foibles and virtues of this mysterious (and for the most part, unlikeable) FBI leader.
The resulting film examines Hoover's life and near 50-year reign from 1924 until he died in 1972, through an objective lens.
What many remember about Hoover are the snippets of gossip concerning his alleged homosexuality, and whether or not his penchant for dressing in women's clothing is fact or fiction. According to Eastwood's biopic, there are no absolutes.
Says DiCaprio, "No one knows for sure what went on in his personal life and, of course, everyone has their opinions." In a time when homophobia was rife, and compounded by his obsessive and dominating mother (Dench) who insisted she'd "rather have a dead son than a daffodil", Hoover kept his relationship with his Tolson, his assistant and constant companion to whom he left his fortune when he died, under wraps.
Says DiCaprio: "He was incredibly repressed and he was an incredibly bottled-up, angry man. He didn't allow himself the capacity to love. He didn't allow himself to have any personal life or personal relationship for fear that it would corrupt the image of the FBI. That was the whole premise of Dustin Lance Black's screenplay. It was a very unique type of relationship between him and Tolson in that regard. It's about two men who are unable to live a normal life and are men of service for the entirety of their life."
"What we do know is that Hoover was always portrayed as a corrupt figure in American history. He had a bulldog persona. He single-handedly changed forensics in our country as to how we catch criminals. He changed federal laws and in what was still a state of the wild, wild west, he created a unified law system that captured criminals efficiently."
In hindsight, many of his ideas are nothing short of extreme, but also representative of its time. "He thought Martin Luther King was the most dangerous man in America. He instilled a lot of fear in this country, particularly during the McCarthy era. He was very ambitious for personal glory and that makes someone pretty unlikeable," says DiCaprio.
No one was impervious to Hoover's power and even Hollywood buckled to his demands.
"He didn't like movies being made about the bad guy. He said, 'Let's get rid of all these damned movies glorifying the American gangster. It's now going to be James Cagney in G Men: The FBI Story, no more James Cagney in The Public Enemy'."
Primarily shot in California, the production was also permitted to film in Washington's Library of Congress and the FBI itself.
For DiCaprio, J. Edgar presented his biggest physical challenge as an actor. "I've never gone through anything like that before. In the same week I'm 19 and also 74-years-old," he says.
Clearly, DiCaprio does not bear any resemblance to Hoover, so there was much to contend with in the physical transformation. Brown contact lenses were applied, a bald cap, a toupee, and many hours in the makeup chair.
He laments, "I found the prosthetic work to be incredibly claustrophobic because you have so many different layers of makeup on you, and I also had an incredible amount of weight that was put on me. Through it, you get this sense that you want to break through the makeup and just breathe again because it did weigh me down a lot. It was very difficult. Very difficult."
Arguably, this is one of DiCaprio's best performances and there is much buzz that his role as Hoover will mark his fourth Oscar nomination.
"I was always intrigued by his personal life and by what motivated him, especially all the stuff through the McCarthy era, the Civil Rights movement, and his fascination with communism. The movie is an interesting reflection of the transition of America during that time," he says. "Ultimately, it's a fascinating portrait of a man."
Lowdown
Who: Leonardo DiCaprio
What: J. Edgar
When: Opens at cinemas February 2
- TimeOut