Moss was born in Chicago, Illinois, of Irish descent on his father's side and his mother was a daughter of immigrants from Italy.

[3] Moss's film credits included roles in In Harm's Way (1965) (his film debut),[1] Chubasco (1968), Pendulum (1969), the Hitchcock movie Topaz (1969), Zig Zag (1970), Fuzz (1972), Stacey (1973), Doctor Death: Seeker of Souls (1973), The Bat People (1974), The Last Married Couple in America (1980) and Raise the Titanic (1980).

Moss also appeared in two episodes of Star Trek: The Original Series: "The Naked Time" as Lt. Joe Tormolen, and "By Any Other Name" as Hanar.

He also appeared in such TV shows as Wheels, Murder, She Wrote, Hogan's Heroes, Matlock, Riptide, Cagney and Lacey, Magnum, P.I., Barnaby Jones, Baa Baa Black Sheep (in the episode "The Meatball Circus"), The Rockford Files, Cannon, Kojak, The Silent Force, Hawaii Five-O, and Bonanza.

In 1974, he appeared in the docudrama teleplay The Missiles of October, playing Kenneth O'Donnell, a special assistant to President John F. Kennedy.