William Kendall Thaw, Sr.

William Thaw Sr. was an American businessman who made his fortune in transportation and banking.

He was born in Pittsburgh, Pennsylvania, on October 12, 1818, to John Thaw and his wife Elizabeth Thomas.

He worked as a clerk in his father's United States Bank of Philadelphia in Pittsburgh. He later switched to McKee, Clark and Co.

By 1842, he and his brother-in-law Thomas Shields Clarke owned steam canal boats, particularly the Pennsylvania and Ohio line. Their company added canal, portage railroad and other steamboat lines.

With the rise of the railroad, Thaw divested the canal business and invested in the new Pennsylvania Company, which managed interests of the Pennsylvania Railroad, in which he was a large shareholder.

Thaw endowed science fellowships at Harvard University and Princeton University and bestowed lavish gifts on art and education. He underwrote the building of the Allegheny Observatory for John Brashear, considered at the time one of the ten best in the world.

"Lyndhurst", the Thaw mansion in Pittsburgh, built 1887-89.

In 1841, William Thaw married Eliza Burd Blair (died 1863). They had five children that survived childhood:

Eliza Thaw, who married George B. Edwards William Thaw Jr. Mary Thaw, who married William R. Thompson Benjamin Thaw Sr. (1859–1933), who married Elma Ellsworth Dows Alexander Blair Thaw (1860–1937) In 1863, after the death of his first wife, he married Mary Sibbet Copley (1843–1929). They had five children that survived childhood:

Harry Kendall Thaw (1871–1947), who would later murder Stanford White. In his will, he left $10,000, less than 1% of his fortune, to wife Evelyn Nesbit. Edward Thaw Josiah Copley Thaw Margaret Copley Thaw (1877–1942), who first married George Lauder Carnegie (1876–1921), nephew of Andrew Carnegie. After his death, she married married Roger, Comte de Périgny and became Countess de Périgny. Alice Cornelia Thaw (1880–1955), who married George Seymour, 7th Marquess of Hertford (1871–1940). They divorced and she married Geoffrey George Whitney Sr. in 1913. In 1887, he commissioned architect Theophilus P. Chandler Jr. to build him a home. The home, which was completed in 1889, was located at 1165 Beechwood Boulevard in the Squirrel Hill neighborhood of Pittsburgh was demolished around 1942.

Thaw died on August 17, 1889.

He is considered to have been one of the 100 wealthiest Americans, having left an enormous fortune. He was the father of Harry Kendall Thaw, whose 1906 murder of noted architect Stanford White resulted in a sensational trial and aftermath.