Leo G. Carroll's father was an Irish-born British military officer. Leo had thought he would make a career of the military. Injuries during World War I forced him to change his military career pursuits.
Leo Carroll never won any movie or television awards. He was nominated for an Emmy for Outstanding Performance by an Actor in a Supporting Role in a Drama in 1966 and 1967 for his protrayal or Waverly in "The Man From U.N.C.L.E." and "The Girl From U.N.C.L.E."