Daniel Radcliffe, Emma Watson and more members of the Harry Potter cast are mourning costar Dame Maggie Smith, who died at age 89 on Friday. While audiences remember Radcliffe, now 35, as The Boy Who Lived and Smith as Professor Minerva McGonagall in the eight-film series,

"I shared the screen with a true definition of greatness." Emma Watson is paying tribute to her late Harry Potter costar Dame Maggie Smith. Watson, who played student Hermione Granger in the film series,