On Monday, Peter Capaldi announced on BBC Radio that season 10 of Dr. Who would be his last. He's leaving on his own accord after three seasons in the role. "I’ve never done one job for three years," he said. "I feel it’s time for me to move on to different challenges. I feel a bit sad but rather wonderful. What a privilege to have done this. You have to be aware of when it’s time to move on. They asked me to stay on — my contract had run out — they asked me to stay. I thought, 'I love this but I don’t know how long I can do it and give it my best.' I want to move on to other challenges, but there’s never been something that’s more special to me." The 13th Doctor will be unveiled during this year's Christmas episode, and people are already calling on BBC to pick a woman or a person of color to portray the iconic character.