Daniel Radcliffe has penned a touching tribute to his late co-star and friend, Alan Rickman.

Radcliffe knew Rickman intimately, of course, making eight Harry Potter films with the well-respected actor.

In a post, Radcliffe calls Rickman one of the greatest actors he will ever work with.

“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. He didn’t have to do that,” he writes in a Google+ post.

Did you see Daniel Radcliffe's note about #AlanRickman? More tributes from the stars: https://t.co/OlyBNU6Y01 pic.twitter.com/kja1ICYt62

— Yahoo Movies (@YahooMovies) January 15, 2016

“People create perceptions of actors based on the parts they played so it might surprise some people to learn that contrary to some of the sterner(or downright scary) characters he played, Alan was extremely kind, generous, self-deprecating and funny. And certain things obviously became even funnier when delivered in his unmistakable double-bass,” Radcliffe says.

Radcliffe says that Rickman was one of the first actors on the Harry Potter set to treat him as a peer, not a child.

Rickman passed away on Thursday at the age of 69 after a long battle with cancer.

By all accounts, Rickman was a joy both on and off set. He will be sorely missed.