John "Mac" Wellington McKelvey (1847–1944) was an American professional baseball shortstop for the Rochester Alert amateur baseball team for a number of years and played one year for the professional New Haven Elm Citys in 1875.

John McKelvey was born in 1847 in Rochester, New York and raised in the city.

The Alerts played a number of regional and national teams and McKelvey gained a reputation for excellent defense.

In 1875, McKelvey joined the New Haven Elm Citys where he played for the entire season batting .229 with 10 RBIs.

This biographical article relating to an American baseball outfielder born in the 1840s is a stub.