During World War II, he enlisted in the United States Army on May 12, 1943, and attended language training at the University of Michigan from 1943 to 1944.

[4][5] While in New York, he began a long career in Broadway theater, first appearing in a production of Irwin Shaw's war drama The Assassin.

(1954), The Silver Chalice (1954), Moonfleet (1955), My Gun Is Quick (1957), Wild on the Beach (1965), Maryjane (1968), The Lawyer (1970), Scandalous John (1971), Time Travelers (1976), Norma Rae (1979) and Intolerable Cruelty (2003).

In 1983, he portrayed the kindly scientist, Professor Hector Jerrold, in the ABC daytime melodrama General Hospital.

[4] Colman played Scrooge over 600 times on stage in A Christmas Carol at the Meadow Brook Theatre in the Detroit area.