John William Killilay (May 24, 1887 – October 21, 1968) was a pitcher in Major League Baseball who played for the Boston Red Sox during the 1911 season.

Listed at 5 ft 11 in (1.80 m), 165 lb., Killilay batted and threw right-handed.

Killilay posted a 4-2 with 28 strikeouts and a 3.54 ERA in 14 appearances, including seven starts, one complete game, and 61 innings of work.

Killilay died in Tulsa, Oklahoma at age 81.

This biographical article relating to an American baseball pitcher born in the 1880s is a stub.