Robert Hallowell Gardiner III (September 9, 1855 – June 15, 1924) was an Episcopal layman and ecumenist, head of the Brotherhood of St. Andrew and one of the founders of the World Council of Churches. A prominent lawyer in Maine and Boston until his retirement for health reasons, he was the great-grandson of Dr. Silvester Gardiner, the founder of Gardiner, Maine, and a trustee for the Gardiner Lyceum school and the Roxbury Latin School.[1][clarification needed]