William John McCoy (September 30, 1834 – June 28, 1897) was an American farmer, Democratic politician, and Wisconsin pioneer.

He served six years in the Wisconsin State Assembly, representing Grant County.

McCoy was born on September 30, 1834, in Argyle, New York.

[1] McCoy was elected to the Assembly in 1875 and served four terms.

[1] Additionally, he was Chairman of the Beetown Board for five years between 1869 and 1876.