Seattle Slew (February 15, 1974 -- May 7, 2002) was an American Thoroughbred race horse who won the Triple Crown in 1977—the tenth of eleven horses to accomplish the feat. He remains the only horse to win the Triple Crown while undefeated. In the Blood-Horse magazine List of the Top 100 U.S. Racehorses of the 20th Century, Seattle Slew is ranked ninth.

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