While several highly regarded Australian actors reportedly went for the role, that someone else was destined to be an Englishman named Tom.

Mr. Hardy said he was daunted by taking on such a seminal part only until he saw the scale of the production, which he likened to a “Technicolor pyschoville circus,” and which in turn, he said, “eradicates me from having to worry about self.”

“It took a huge weight off my shoulders when I realized how big the piece was,” Mr. Hardy said. “It was 50 miles to the horizon, overseas, 360 degrees of sand and sky, and then there was this just sort of S-and-M party, do you know what I mean? With Hells Angels types right in the middle of it, with parasails and explosions. And it was very weird. It was fantastic.”

Mr. Hardy met to chat in Las Vegas, having flown in the night before from Britain to promote the film at CinemaCon, an annual trade show for the National Association of Theater Owners, which, amazingly, goes by the acronym NATO. His bushy beard and bare scalp look had gotten its own article in The Daily Mail, and was in place for “The Revenant,” which he had been filming in Calgary, Alberta, with Leonardo DiCaprio and the Oscar-winning director Alejandro G. Iñárritu.

“I’m not very interesting, by the way,” Mr. Hardy declared, as we settled into his upper-floor suite at Caesars Palace. “I’m monosyllabic and sometimes just allowed to play in the corner. And I might express myself physically instead, if that’s all right. Cool?”

This introduction had the effect, most likely intended of leaving his listener disarmed yet slightly wary; you can relate to the guy, but what might he do next? This is a signature Tom Hardy move, something that helped him win the role of Max (for which he auditioned). Mr. Miller was looking for someone who had the “animal charisma” of Mr. Gibson while conveying a sense of both accessibility — “You want to be his best friend,” Mr. Miller said — and mystery.