Glass played the mysterious Shepherd Book in the beloved show starting in 2002, and also reprised his role in the 2005 film "Serenity."
Nathan Fillion wrote, "'Shepard, don't move.' 'Won't go far.' We love you, Ron Glass. Don't go far."
"He got there with grace, humor & enormous heart. He was, among so many other things, my Shepherd. Raise, appropriately, a glass. Rest, Ron," wrote the show's creator, Joss Whedon. He also posting a video of the late actor.
Jewel Staite posted a picture of herself on set with Glass. "This is me acting like an idiot just so I could hear Ron Glass laugh," she wrote. "He was the kind of person that remembered the details, that asked about your family's well-being. He hugged hard and often. He would laugh till he cried at a sick joke and top it with a worse one. He loved a Grey Goose crantini and spilled one on my white jeans in the heat of telling a story, and then just said, 'Girl, those were ugly pants anyway.' I adored him. Everybody did. I love you, Ron. Can't wait to see you again. 'I don't care what you believe. Just believe it.'"
Alan Tudyk tweeted a tribute: "Ron Glass was one of the greatest actors to work with. His laugh was beyond infectious and his generosity was ever present. Ron Glass was also a sassy smart ass and I prize that very much. A leaf on the wind."
Adam Baldwin posted a clip from the show with the caption, "Happy rebirth, dear Ron Glass. Among the kindest and gentlest souls to have walked this earth with us."
Sean Maher wrote, "Ron Glass. What an honor it was to know you, to work beside you and to have called you my friend. You will be missed. I love you sir."
See photos of Ron Glass throughout his life: