Patrick Stewart, "X-Men" and "Star Trek" star, dies; The actor was 86 years old. Stewart died Wednesday at his home in Los Angeles after battling Alzheimer's disease and Lewy body dementia, his spokeswoman Kelly Bush Novak said. The actor played Professor Charles Xavier, also known as Professor X, and Captain Jean-Luc Picard in Star Trek. Patrick also appeared in the new "Avengers", which should be released this year.