John Harger Stewart (born March 31, 1940, Cleveland) is an American tenor, conductor, and voice teacher who had an active international singing career in concerts and operas from 1964 to 1990.
He began his career singing regularly with the Santa Fe Opera from the mid-1960s through the early 1970s; after which he appeared only periodically in Santa Fe up through the mid-1980s.
He was particularly active with the New York City Opera during the 1970s and 1980s, and with the Frankfurt Opera from the mid-1970s through 1990.