Everett MacMillian Clark was born in Quincy, Massachusetts in 1893. After the war he moved to New York with radio pioneer Lee De Forest at station WJZ. Clark recorded with early labels Victor, Columbia, Edison and many others. Later Clark became a banker in Brooklyn and a Vice President of Manufacturers Trust Company. Everett Clark might have been the voice for Grampy from 1935-1937.
The voice of Grampy has only been debated and not exactly identified.
Jack Mercer (1935-1937) credited by the modern day Fleischer Studios.