Johnstown (March 12, 1936 – May 14, 1950) was an American Hall of Fame Thoroughbred racehorse who won two out of every three races he competed in.
After a successful season racing at age two when he won seven of his twelve starts, in the spring of 1939 Johnstown gave trainer Sunny Jim Fitzsimmons his third straight Wood Memorial Stakes, an important stepping stone to the U.S.
The heavy favorite going into the Kentucky Derby, Johnstown got off to a slow start under jockey James Stout, then he took command by the mile pole and defeated Challedon by eight lengths, tying the (still current, 2015) record for margin of victory.
He later won several more important races and wound up his highly successful season with seven wins in nine starts.
Retired to stud at Claiborne Farm, Johnstown met with modest success as a sire, producing winners of only six stakes races.