Complex sentence: William Johnstone is also the name of a Hollywood film composer, as well as a movie and live radio actor who appeared in supporting roles in films and was active in the 1940's and' 50's.
Split into simpler sentences: William Johnstone is also the name of a Hollywood film composer, as well as a movie and live radio actor who appeared in supporting roles in films. He was active mainly in the 1940's and' 50's.