Condolences and heartfelt posts have been pouring in from every corner of social media after news of Alan Rickman's death broke Thursday morning. While many of the tweets, Facebook updates, and more have been from fans of the award-winning actor, some have come from his former co-stars. Most recently, both Emma Watson and Daniel Radcliffe, both of whom starred alongside Rickman, 69, in "Harry Potter," took to the internet to express their sadness. 

As was reported by Buzzfeed, Racliffe, 26, shared a lengthy letter of sorts with fans via Google+, his only known social media account. In the piece he called Rickman, who played Professor Severus Snape in the "Harry Potter" films, "one of the greatest actors" he'd ever worked with. He recalled his co-star's kind words on and off set, telling fans he found him to be "encouraging." Radcliffe shared that Rickman had been a great supporter of his work, coming to most, if not all, of his theatrical performances in London and New York. The fellow Londoner added that while many may equate Rickman with characters like Snape, he was the total opposite. Radcliffe called him "extremely kind, generous, self-deprecating and funny."

"Alan Rickman is undoubtedly one of the greatest actors I will ever work with. He is also, one of the loyalest and most supportive people I've ever met in the film industry. He was so encouraging of me both on set and in the years post-Potter. I'm pretty sure he came and saw everything I ever did on stage both in London and New York," Radcliffe wrote. "He didn't have to do that. I know other people who've been friends with him for much much longer than I have and they all say 'if you call Alan, it doesn't matter where in the world he is or how busy he is with what he's doing, he'll get back to you within a day.'"

Rupert Grint, Daniel Radcliffe, Emma Watson Daniel Radcliffe (center) and Emma Watson (right), photographed alongside "Harry Potter" co-star Rupert Grint at the New York premiere of "Harry Potter and the Deathly Hallows: Part Two" on July 11, 2011, have spoken out about the death of co-star Alan Rickman on social media. Photo: Getty Images

Watson, 25, who played the strong-willed and intelligent Hermione Granger in the"Harry Potter" franchise, chose to share her feelings in an emotional Facebook post. She told her followers she was deeply saddened to learn that Rickman had died, adding that she was "so lucky" to have had the opportunity to work with him. Watson referred to her fellow "Harry Potter" star as being "a special man and actor" before sending a message of love his way. She then tweeted a photo of the star with a quote of his about feminism.

Radcliffe and Watson aren't the only stars from the film speaking out about losing Rickman. Oliver and James Phelps both sent messages of shock and grief to Twitter followers and "Potter" fans Thursday. The twin acting duo, who starred as George and Fred Weasley in "Harry Potter," both seemed to be completely caught off guard by the tragic news. Warwick Davis, a fellow member of the Wizarding World's esteemed Hogwarts faculty, echoed Watson and Radcliffe's statements, writing that he was "honoured to have shared the screen" with the likes of Rickman. 

J.K. Rowling, responsible for writing the books on which the "Harry Potter" films are based, also took to Twitter Thursday to discuss Rickman's passing. She told followers she was at a loss for words after learning that the actor had died before sending her well-wishes to Rima Horton, Rickman's now-widowed wife.

Rickman's death was confirmed by his family members. He reportedly died after battling cancer.