William Andrews Clark Sr. (January 8, 1839 – March 2, 1925) was an American entrepreneur, involved with mining, banking, and railroads, as well as a politician.

Though his claim paid only moderately, Clark invested his earnings in becoming a trader, driving mules back and forth between Salt Lake City and the boomtowns of Montana to transport eggs and other basic supplies.

He made a fortune with copper mining, small smelters, electric power companies, newspapers, railroads (trolley lines around Butte and the San Pedro, Los Angeles and Salt Lake Railroad from Salt Lake City, Utah to San Pedro and Los Angeles, California), and other businesses, becoming known as one of three "Copper Kings" of Butte, Montana, along with Marcus Daly and F. Augustus Heinze.

The November 1903 Congressional Directory notes that Clark "was a major of a battalion that pursued Chief Joseph and his band in the Nez Perces invasion of 1877.

[7] [8] In a 1907 essay, Mark Twain, who was a close friend of Clark's rival, Henry H. Rogers, an organizer of the Amalgamated Copper Mining Company,[9] portrayed Clark as the very embodiment of Gilded Age excess and corruption: He is as rotten a human being as can be found anywhere under the flag; he is a shame to the American nation, and no one has helped to send him to the Senate who did not know that his proper place was the penitentiary, with a ball and chain on his legs.

Clark donated 135 acres to the Girl Scouts in honor of his elder daughter (by his second wife), Louise Amelia Andrée (who died at age 16 of meningitis), who had been very happy there.

Today, the William Andrews Clark Memorial Library specializes in English literature and history from 1641 to 1800, materials related to Oscar Wilde and his associates, and fine printing.

Huguette (pronounced oo-GETT), born in Paris, France in June 1906, was the youngest child of Clark with his second wife, Anna Eugenia La Chapelle.

For many years, she lived in three combined apartments, with a total of 42 rooms, on New York's Fifth Avenue at 72nd Street, overlooking Central Park.

These articles were the basis for the 2013 bestselling book Empty Mansions: The Mysterious Life of Huguette Clark and the Spending of a Great American Fortune.

[19] Huguette's extraordinary collection of arts and antiquities were consigned to go on the auction block at Christie's in June 2014, over three years after her death.

He was among the 1,514 who died on April 15, 1912, after the ship struck an iceberg at 2:20 a.m. Walter's wife, Virginia, was rescued by the RMS Carpathia, and arrived in New York City a widow.

The city of Las Vegas was established as a maintenance stop for Clark's San Pedro, Los Angeles and Salt Lake Railroad.