While keeping his surname fixed, Kellogg was very changeable about his first and middle names and initials. Back in the late 1930s, when he began seeking work as an actor, he was known as "Giles Kellogg" and "Giles V. Kellogg" (in "Academy Players Directory" and acting on Broadway). Later, once he began getting regular film acting jobs, he changed to "John Kellogg" and "John G. Kellogg." Clearly, the "G." stood for "Giles," but it's unknown what the "V." stood for.