Stewart was known for his roles as Captain Jean-Luc Picard in Star Trek and Professor Charles Xavier in the X-Men films.
Fellow Star Trek alum William Shatner and X-Men co-star Hugh Jackman also praised the veteran actor, who died from Alzheimer's disease and Lewy body dementia.
Ian McKellen
"Before everything else, Patrick was defined by being born and bred in Yorkshire ... You could hear it in his accented voice and in the stern honesty with which he told you what he thought and felt. Yorkshiremen have no truck with half-truths or avoidance of big issues. He wore his heart on his sleeve, which made him a man to rely on, to admire and in my case, love.
"... he never forsook his origins: and the proudest achievement of the most respected and beloved actor of his generation on either side of the Atlantic, was his appointment as chancellor of Huddersfield University in Yorkshire.
William Shatner
"What a heartbreaking week it has been. Sir Patrick Stewart was a friend, a colleague, and a magnificent actor. From the stage to the bridge of the Enterprise, he brought intelligence, grace, and a deep sense of humanity to everything he did. Captain Picard stood for the best of us, and so did the man who played him. I was filled with affection and admiration for him and his work."
Hugh Jackman
"We lost one of the greats of stage and screen today. And, in my book, a tremendous friend and man. I learned so much from him. I will miss you, Patrick Stewart, all of my days."
Seth MacFarlane
"Patrick was one of those icons who we somehow all took for granted would always be with us. I grew up as a fan, and was later gifted the privilege of becoming a colleague and friend, working with him for many years on American Dad!, Family Guy, and Ted. He was that rare actor who could take any bit of dialogue and elevate it, making a good writer sound great, and a great writer sound masterful. He was also as humble as they come."
George Takei
"Fans across the world mourn the passing of a true and irreplaceable legend. As Captain Jean-Luc Picard, Patrick Stewart took the starship Enterprise to places it had never gone before. He inspired a whole next generation of star-gazers who looked longingly ahead to a brighter future for all humanity. Our hearts are heavy, indeed. Rest in the heavens, Captain."
Marvel Studios
"All of us at Marvel Studios are deeply saddened by the passing of Sir Patrick Stewart. Sir Patrick brought Professor Charles Xavier to life with extraordinary grace, intelligence, and humanity, defining the character for generations of fans, from X-Men to Logan to Avengers: Doomsday. He was a singular talent, a generous collaborator, and a true gentleman. Our hearts go out to his wife Sunny, his children, his friends, and the countless fans around the world whose lives he touched with his art."
Ricky Gervais
"RIP Patrick Stewart. What an actor. I still can't believe he agreed to do this scene (from the comedy series Extras). And he didn't even mind when I ruined every take. Legend."
with PA