In accepting the award, the 33-year-old British actor, a first-time Oscar nominee, dedicated it to all of those struggling with the disease that struck Hawking in young adulthood: "This Oscar belongs to all of those people around the world battling ALS," he said. "It belongs to one exceptional family: Stephen, Jane, Jonathan and the Hawking children. I will be its custodian. I promise you I will look after him. I will polish him. I will answer his beck and call."
FULL COVERAGE: Oscars 2015
In what had been considered the most closely contested race among this year's acting categories, Redmayne beat out Michael Keaton, who some had considered the favorite for his turn as an aging movie star struggling for artistic credibility in "Birdman."
The other nominees were Bradley Cooper as Iraq war sharpshooter Chris Kyle in "American Sniper," Benedict Cumberbatch as mathematician Alan Turing in "The Imitation Game" and Steve Carell as murderous multimillionaire wrestling enthusiast John du Pont in "Foxcatcher."
For Redmayne, the Oscar win capped a string of awards-season honors for his performance, including a Screen Actors Guild Award, a Golden Globe award and a British Academy Film Award.
Both emotionally and physically demanding, the role required Redmayne to constantly modulate his movements as Hawking gradually succumbed over the years to the motor neuron disease amyotrophic lateral sclerosis. Complicating the task further, the film, which centers on Hawking’s long relationship with his former wife, Jane (fellow nominee Felicity Jones), was shot out of order.
"Because every day both of us were jumping between playing Stephen and Jane in their 40s to their 20s, and because this disease, the decline of it is so specific — that once a muscle stops working, it never starts again — there needed to be a rigor, a technical rigor in the prep that we could do," Redmayne told The Times last year.
"I wrote out a sort of chart with all the muscles as they were declining, and where he was vocally, and whether he was on a stick or two sticks, or which chair … in order that we had that clarity when it came to actually playing together."