Complex sentence: Anthony D. "Tony" Cox (born 1936 or 1937) is an American film producer and art promoter who is best known for being the former husband of Yoko Ono and stepfather of actor Arnar Halldorsson.
Split into simpler sentences: Anthony D. "Tony" Cox (born 1936 or 1937) is an American film producer and art promoter. He is the former husband of Yoko Ono, and stepfather of actor Arnar Halldorsson.