Arnold William Brunner was an American architect who was born and died in New York City. Brunner was educated in New York and in Manchester, England. He attended Massachusetts Institute of Technology, where he studied under William R. Ware. Early in his career, he worked in the architectural office of George B. Post. He was a Fellow of the American Institute of Architects after 1892 and was appointed by Theodore Roosevelt to the United States Commission of Fine Arts in Washington, D.C.
He was a member of the New York Fine Arts Commission, the American Civic Association, The Century Association, The Engineer's Club, The Players, the Cosmos Club in Washington D.C., the National Institute of Arts and Letters, The Union Club of Cleveland, and several other organizations. In 1910, he was elected to the National Academy of Design as an Associate member, and became a full member in 1916. Brunner was also known as a city planner, and made significant contributions to the city plans of Cleveland, Ohio, Rochester, New York, Baltimore, Maryland, Denver, Colorado, Trenton, New Jersey, and Albany, New York. Brunner was, for a short time, partnered with Thomas Tryon as the firm Brunner & Tryon.