Harris changed in 1932 at the age of 17 years, officially his name to Harris. He attended Fordham University and completed his study of pharmacy in 1936.
He then played at various theaters before he got in 1942 a first engagement on Broadway. A few years later, he starred in A Flag Is Born a starring role alongside Marlon Brando. From 1949 he also worked for television. He made guest appearances on several television shows and series such as Peter Gunn, Bonanza, Zorro and The Twilight Zone. Between 1959 and 1965 he played in 73 episodes in the based on the film The Third Man The Third Man series. From 1965 to 1968 he played the role of Dr. Zachary Smith in the series Lost between alien worlds in 83 episodes. He had his last series starring role in 1977 in the Space Academy.
In the late 1970s, Harris retired from acting and worked as a voice actor. One of his first speaking roles was the Cylon Lucifer in the series Battlestar Galactica. Harris often worked for Disney and was with A Bug's Life and Toy Story 2, Pixar involved in two productions in 1998.