William C. Kingsley (c. 1833–1885) was an American construction contractor who is best known for being one of the main figures involved in the creation of the Brooklyn Bridge.
Kingsley became the driving force behind that project, hiring Colonel Julius Walker Adams, a civil engineer who had worked with him on the Brooklyn sewers, to come up with a design and to prepare cost estimates.
His role was to come with a lowball estimate of the cost of the bridge, allowing Kingsley and its other promoters to gain the necessary approvals from public officials.
Soon, he was named its superintendent, and a motion, proposed by none other than Boss Tweed and passed by the other trustees, authorized payment to Kingsley & Keeney of 15% of all construction costs.
In 1873, after Tweed had fallen from power, Kingsley & Keeney's contract with the Bridge Company was renegotiated, and its payment was slashed to the much smaller flat fee of $10,000 (equal to about $300,000 in 2023) per year.