Chester Alan "Gavin" Arthur III (March 21, 1901 – April 28, 1972) was an American astrologer and sexologist. He was the grandson of Chester A. Arthur, the twenty-first president of the United States. He received his early education from Columbia College and later joined the Philolexian Society. He left his college and participated in the Irish Republican Movement. During his time in Ireland, he began going by the name Gavin.