VIDEO : Ian McKellen Gives Incredible Tribute to Friend Alan Rickman

Tributes for actor Alan Rickman, who died Thursday, have been pouring in all day on social media. J.K. Rowling, Daniel Radcliffe, Emma Watson and the rest of the Harry Potter cast have been sharing their memories of the actor, and a vast number of celebrities have also taken to Twitter and Instagram to pay tribute to him. Sir Ian McKellen's personal tribute is a lengthy, poignant account of a man he clearly admired greatly as both a colleague and a friend. He wrote, "He leaves a multitude of fans and friends, grateful and bereft."