Nimoy will play the mysterious William Bell, founder of Massive Dynamic and former lab partner of Walter Bishop played by John Noble.
"It was a delight to work with Mr. Nimoy on Star Trek," said Abrams. "The idea that he will play the mysterious, much-referenced William Bell is a thrill. I know I sound like a goofy fan boy, but I can’t help it. Leonard is an icon of the genre and such a wonderful actor. To have him come on board Fringe is a mind-blowing honor."
Nimoy will appear in the season finale with a view to further appearances next season.