John S. Malarkey (May 4, 1872 – October 29, 1949) was a 19th-century right handed pitcher in Major League Baseball who played for the Washington Senators, Chicago Orphans and Boston Beaneaters in a span of six seasons from 1894 to 1903.

[1] Malarkey entered the records books when he became the only pitcher to date in major league history to earn a victory by hitting his own walk-off home run.

On September 10, 1902, Malarkey hit a solo shot against St. Louis Cardinals pitcher Mike O'Neill in the bottom of the 11th inning to give the Beaneaters a 4–3 victory in the second game of a doubleheader at Boston's South End Grounds.

Besides, he posted a strong 2.59 earned run average and was one of only four ERA qualifiers in the majors who did not surrender a single home run, being the others Ed Siever of the Detroit Tigers[3] and Ed Doheny and Jesse Tannehill, both of the Pittsburgh Pirates.

[1] After his baseball days, Malarkey worked for the Erie Railroad and lived in Marion, Ohio.