The BBC said while Britain's Mirren was honored for her role in the Princess Diana film, "The Queen," festival officials named American Affleck best actor for his portrayal of former "Superman" actor George Reeves in the drama, "Hollywoodland."

"It's always terrifying seeing your movie take its first steps," the 61-year-old actress said while accepting her award, "but it's an incredible honor for our film to take them at the Venice festival."

"The Queen," directed by Stephen Frears and written by Peter Morgan, also captured the festival's best screenplay award.

With 22 films competing for the Venice event's awards, the Chinese film "Still Life" followed in the footsteps of last year's winner "Brokeback Mountain" by being taking home the festival's Golden Lion prize for best film, said the BBC.