William Joseph Gainey (born May 27, 1956) is a retired United States Army soldier who served as the first senior enlisted advisor to the chairman of the Joint Chiefs of Staff.

Gainey enlisted in the United States Army under the Delayed Entry Program in 1974 and entered basic training at Fort Knox, Kentucky on June 17, 1975.

Thereafter, he served in a number of enlisted leadership positions, from gunner to command sergeant major.

On October 1, 2005 Gainey was appointed the first Senior Enlisted Advisor to the Chairman of the Joint Chiefs of Staff, a newly created position established to advise the Chairman on matters of professional development of enlisted personnel assigned to joint billets.

[4] Since his retirement from the army, Gainey has taken a board member position at Trident University International.