William Kissam Vanderbilt I (December 12, 1849 – July 22, 1920[1]) was an American heir, businessman, philanthropist, and horse breeder.

[2] William Kissam Vanderbilt I was born on December 12, 1849, in New Dorp, New York, on Staten Island.

[6] After his divorce from Alva, he moved to France where he built a château and established the Haras du Quesnay horse racing stable and breeding farm near Deauville in France's famous horse region of Lower Normandy.

Vanderbilt's horses won a number of important races in France including: On April 20, 1875, Vanderbilt married his first wife, Alva Erskine Smith, daughter of Murray Forbes Smith and Phoebe Ann Desha.

[7] Together, they had three children:[2] Alva later coerced Consuelo into marrying Charles Spencer-Churchill, 9th Duke of Marlborough on November 6, 1895.

[1] His remains were brought home and interred in the Vanderbilt family mausoleum in New Dorp, Staten Island, New York.

[11] In World War II, the United States liberty ship SS William K. Vanderbilt was named in his honor.

[14] Contemporary estimates reported in newspapers in August 1920 speculated that the total estate of Vanderbilt was between $40,000,000 to $100,000,000.

[15] The Gross Value of the Estate was reported to be $54,530,966.59 following the decree fixing the income tax payable in the Suffolk County Surrogate’s Court on 6 March 1923.