Earlier this year, the actor revealed his struggle with the lung disease emphysema - caused, he said, by a 50-year smoking habit.

BBC: Obituary: Richard Briers

He was, by all reports, a good programmer in his own right, and had vision and courage, but was sidetracked from the rise of Microsoft by a struggle with disease.

FORBES: Paul Allen's Lawyer Says He's a Genius

With his resignation, Pope Benedict has chosen a starkly different path than his predecessor, John Paul II, whose long struggle with Parkinson's disease played out before eyes of the world before his death in 2005.

WSJ: Pope Benedict XVI to Resign