Patrick Stewart, the British actor widely known for his roles in the “Star Trek” and “X-Men” franchises, died Wednesday at his home in Los Angeles. He was 86. According to a statement posted on his social media accounts, Stewart’s passing followed a “brief and poignant journey” with Alzheimer’s disease and Lewy body dementia.

Born on July 13, 1940, in Mirfield, West Yorkshire, Stewart began his career on the British stage. He trained at the Bristol Old Vic Drama School and made his professional debut in 1959. He built a distinguished reputation performing classical theatre with the Royal Shakespeare Company and London’s National Theatre before transitioning to television and film.

Stewart achieved international fame in his late 40s for his portrayal of Captain Jean-Luc Picard in the 1987 debut of “Star Trek: The Next Generation.” The role succeeded William Shatner’s Captain Kirk and quickly established Stewart as a leading figure in science fiction television. His authoritative performance was marked by memorable catchphrases such as “Make it so” and “Engage!” Initially met with skepticism in American television—including a description from the Los Angeles Times as an “unknown British Shakespearean actor”—Stewart credited his extensive Shakespearean background for preparing him for the role.

In 2000, Stewart expanded his global audience as Professor Charles Xavier, the mentor of mutant superheroes, in the “X-Men” film series. His portrayal brought gravitas to the character and earned acclaim from Marvel Studios, which highlighted his more than 25 years in the role. Hugh Jackman, who played Wolverine alongside Stewart, remembered him as a remarkable actor and a close friend. Stewart’s final film appearance as Professor Xavier is set for December’s release of “Avengers: Doomsday.”

Despite his success in Hollywood, Stewart remained deeply committed to theatre throughout his career. He returned often to the stage, earning two Olivier Awards and being recognized by the Royal Shakespeare Company as “a colossus of both stage and screen” and one of the finest classical actors of his generation.

Stewart was the third of three brothers in a working-class family and left school at 15 to pursue acting. His enduring contributions to both stage and screen have left a significant legacy in entertainment worldwide.