William Letts Oliver (August 6, 1844 – November 4, 1918) was a mining engineer who, along with Freeborn Fletter, founded the California Cap Company, the first U.S. manufacturer of blasting caps used for explosives in mining. He was also one of the principal owners of the Oliver Manufacturing Company.
W. L. Oliver and his son Roland were amateur photographers, with over 2,700 of their photos collated on the Online Archive of California.
Upon W. L. Oliver’s death in 1918, Roland Oliver became president of the California Cap Company, which ceased operating in the 1940’s.
W. L. Oliver’s funeral was held at the family home on Thursday, Nov. 7, 1918. He is buried in Mountain View Cemetery in a mausoleum just below "Millionaire's Row."