John Thomas Grimes (April 17, 1869 – January 17, 1964) was an American professional baseball player who played in three games for the St. Louis Browns during the 1897 season.

He was born in Baltimore, Maryland and died in San Francisco at the age of 94.

At the time of his death, he was the oldest living former major league player.

On the 31st of July, Grimes hit six St Louis Browns hitters, setting a National League record that still stands today.

This biographical article relating to an American baseball pitcher born in the 1860s is a stub.