Rickman, who died on Thursday at the age of 69, played the character of Professor Severus Snape in the "Harry Potter" films.
Fans began leaving flowers, photos and notes in memory of Rickman at Platform 9 3/4 at King's Cross Station in London, which is the fictional location from the "Harry Potter" franchise where one departs for Hogwarts on the Hogwarts Express.
The makeshift memorial for Rickman grew as the day went on, with more and more fans visiting Platform 9 3/4 to pay their respects.
Flowers at Platform 9 3/4 in Kings Cross pic.twitter.com/shnRPF7KSV— Martin (@Martin_2052) January 15, 2016
Alan Rickman memorial at Platform 9 3/4 pic.twitter.com/pZx7WPqhKB— Charlotte Katherine (@charlotte_kath) January 15, 2016
Rickman's "Harry Potter" co-stars paid tribute to the British actor on social media following the news of his death.
"Potter" scribe J.K. Rowling wrote that Rickman was "a magnificent actor & a wonderful man," and actor Daniel Radcliffe, who played Harry Potter in the "Potter" films, described Rickman in a heartfelt essay as "extremely kind, generous, self-deprecating and funny."
"Film sets and theatre stages are all far poorer for the loss of this great actor and man," Radcliffe wrote.