Reginald Claypoole Vanderbilt (1880 -September 4, 1925) was a member of the prominent United States Vanderbilt family.

Known as Reggie, he was the youngest son of American railroad magnate Cornelius Vanderbilt II and his wife Alice Claypoole Gwynne (1845-1934). He attended Yale University, where he acquired a reputation for dissipation—and no diploma.

His first wife, whom he married on April 14, 1903, was Cathleen Gebhard Neilson. They had a daughter, Cathleen (1904-1944), and were divorced in 1919. His second wife, whom he married in 1923, was Gloria Laura Mercedes Morgan (1904-1965). By the time Reggie Vanderbilt met her, he had already squandered the $7 million willed to him by his late father and was using up a $5 million trust set up for him by his grandfather.

A horse enthusiast, he lived at Sandy Point Farm, in Newport, Rhode Island and in 1917, founded the United States Equestrian Federation (USEF).

Reginald Vanderbilt died of liver failure due to alcohol abuse and was interred in the Vanderbilt family vault in the Moravian Cemetery at New Dorp on Staten Island, New York.

He left a $4 million Trust for his daughter Gloria to be administered by her mother but it caused a much publicized court case for the custody of his daughter with his sister, Gertrude Vanderbilt Whitney who eventually won custody in 1934.