Da Unraveling the tale behind the Apple logo (CNN, 2011):

[Alan Turing] bit into an apple he had laced with cyanide […] And so, the story goes, when two Stanford entrepreneurs were looking for a logo for their brand new computer company, they remembered Turing and his contribution to their field. They chose an apple — not a complete apple, but one with a bite taken out of it. […The] evidence now points in a more prosaic direction. In a 2009 interview with CreativeBits, Rob Janoff, the man who drew the logo […]

“I’m afraid it [the Turing story] didn’t have a thing to do with it,” he said. “It’s a wonderful urban legend.”