Gregory John Holbrock (June 21, 1906 – September 4, 1992) was an American attorney, politician and one-term member of the United States House of Representatives from Ohio from 1941 to 1943.
His father was a shoemaker by trade who became a successful merchant and partner with his younger brother William G. Holbrock in the Holbrock Brothers Dry Goods store in Hamilton and a branch, Middletown Dry Goods, in Middletown, Ohio.
He met Bernice A. Heringer (1909–2005) at Xavier University and on June 1, 1938, they married; they had five children and 10 grandchildren.
Holbrock was elected from Ohio's third district as a moderate Democrat to the Seventy-seventh Congress and served one term.
He became chairman of the Butler County Democratic Executive Committee in 1950 and served sixteen years in that capacity until 1966.