There's not much Louis Theroux hasn't experienced of humanity. In more than 25 years of documentary making, he's moved in multiple worlds including those of neo-Nazis, Scientologists, pornography stars, those living with dementia - and Jimmy Savile.
While his approach has altered over the years, from comic gonzo to sober inquisitor, Theroux's ability to extract uncomfortable truths without confrontation has not.
Yet, the one person we don't get to know is Theroux himself. The questions are simple. The expression inscrutable. Only his eyebrows sometimes go rogue. In other words, he gives his interviewee space to show who they are.
Epithets from "faux-naive", "impenetrable" and "wacky" have been employed in an attempt to define him. Theroux says he can, up to point, understand why.
"I plead guilty to, back in the day of Weird Weekends and When Louis Met, sometimes being a 'wacky' satirist, finding fringe people in marginal, wrongheaded or poisoned lifestyles and having fun with them, making them look a bit silly," he says.
"Now I cover stories I'm interested in, funny or not.
"We used to say, 'Where are the laughs?' as a way of eliminating a subject. But it's not about being Jeremy Paxman or David Frost, but being engaging, exciting and interesting and being the best me I can."
As Theroux edges towards 50, his latest project - a memoir - could help unmask the "real" him.
In Gotta Get Theroux This, he turns the focus inwards, to the workings of his TV world and his complicated mind. The title's pun comes from the ironic "cult of Louis" that spawned a range of Theroux-themed merchandise. Theroux wanted to "repurpose the meme, which never struck me as really that funny. Any pun on my name, I've heard a million times".