As manager John Terrence Slattery (January 6, 1878 – July 17, 1949) was a catcher and first baseman for the Boston Americans, Cleveland Naps, Chicago White Sox, St. Louis Cardinals, and the Washington Senators for parts of four seasons between 1901 and 1909.

He was never used regularly, and some of his Major League stops were very short (he played only four games for the Naps).

He was head baseball coach at Harvard from 1920 to 1923 and Boston College from 1924 to 1927.

He resigned as manager and owner Emil Fuchs hired Rogers Hornsby to replace him.

This biographical article relating to a United States baseball catcher born in the 1870s is a stub.