Sir Patrick Stewart, the British actor famous for playing Captain Jean-Luc Picard in Star Trek and Professor Charles Xavier in the X-Men films, has died at 86. He died at his Los Angeles home after a brief illness with Alzheimer's disease and Lewy Body Dementia, his family said Thursday.

Sir Ian McKellen, his X-Men co-star and longtime friend, called him "the most respected and beloved actor of his generation". McKellen, who officiated Stewart's 2013 wedding, recalled first meeting him as young actors in the Royal Shakespeare Company and noted that Stewart had been cautious about taking the Star Trek role. "He took the risk and thank goodness for us all that he did," McKellen said.

William Shatner, who also played a captain in Star Trek, said Stewart brought "intelligence, grace and a deep sense of humanity to everything he did". Hugh Jackman, his X-Men co-star, called him "a tremendous friend and man" and "one of the greats of stage and screen".

Stewart played Captain Picard in more than 170 Star Trek episodes between 1987 and 1994, four feature films, and returned to the role for Star Trek: Picard in 2020. His final film appearance will be as Professor X in the upcoming Avengers: Doomsday film.

Born in Mirfield, Yorkshire in 1940, Stewart joined the Royal Shakespeare Company in 1966. He was knighted by Queen Elizabeth II in 2010. He is survived by his wife Sunny Ozell and two adult children from his first marriage.