I see in the news that Brian May has finished his PhD thesis after thirty-six years. (BBC News: Queen star hands in science PhD and Live!: Brian May Hands in Thesis for some pictures.) May will now have to defend the thesis at his viva on the 23rd. Vivas are nominally open - I wonder if this will be the first time people will have to be turned away due to limited space?!
But before anyone asks, I don't plan to still be finishing my thesis when I'm sixty!