Keyser was born in Baltimore, Maryland on November 23, 1835, the son of Samuel Stouffer Keyser and Elizabeth Wyman Keyser. Samuel eventually moved to New York City to make his way in business there, while William stayed in Baltimore to manage his father"s warehouses.
He was educated at various private schools in Baltimore, and entered Saint Timothy"s Academy in Catonsville, Maryland in 1846.
He was active in the firm, as well as the Abbott Iron Company and the Baltimore Company, throughout the 1860s. They had three children who lived to adulthood: Robert Brent Keyser, Henry Irvine Keyser, and Mathilde Lawrence Keyser. In 1870, William Keyser became involved with the Baltimore and Ohio Railroad, taking a position as second vice-president during the term of its president, John Work Garrett.
The town of Keyser, West Virginia was named for him.
While at the, he was instrumental in labor negotiations during the 1871 and 1877 railroad workers strikes. Keyser next ventured into copper manufacturing.
In 1882, the court appointed him to oversee the financial affairs of Pope and Cole, a local copper processor. The company had declared bankruptcy, and Keyser, as one of their largest creditors, had a vested interest in seeing them regain solvency.
His association with Pope and Cole piqued his interest in the copper industry.
He eventually reestablished Pope & Cole as the Baltimore Company and purchased the Baltimore Smelting and Rolling Company. His entry into copper production allowed him to amass a fortune larger than if he had stayed with the railroad. Keyser put his money to many philanthropic uses.
He donated funds for a hall at Hannah More Academy in Reisterstown, and was instrumental in the founding of the JHU Homewood campus.
The Committee prepared street and dock improvement plans, which were adopted. Keyser died suddenly at his summer home, Brentwood, on June 3, 1904.
Before his death in June, 1904, Keyser was appointed a member of the Citizens" Emergency Committee which was charged with developing a plan for rebuilding the downtown after the calamitous Baltimore fire of February 1904.
