Showbiz
Rex Features
The Doctor Who star's performance in Hamlet was named the event of the year, while Hartnett scooped the best newcomer prize for his role in Rain Man.
Accepting his trophy via video link from Los Angeles, Hartnett said: "Being on stage in the West End production of Rain Man was a thrilling new experience.
"Everyone worked incredibly hard, and made me feel welcome. I am thankful to the audiences for coming out and supporting us."
Around 35,000 theatre fans voted for awards which were presented by Gavin & Stacey stars James Corden and Sheridan Smith.
Other winners included Eddie Izzard, who was named the best solo performer for his show Stripped, and Kenneth Branagh, who took home the best actor gong for his turn in Ivanov.
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