T M Opera O (Japanese: テイエムオペラオー, March 13, 1996 – May 2018) was a champion Japanese thoroughbred racehorse, and was the world's all-time leading money earner at the time of his retirement in 2001. In 1999, he was the champion three-year-old colt in Japan after winning the Satsuki Sho (Japanese 2000 Guineas). At age four, he was the Japanese Horse of the Year and champion older horse after an undefeated season that included wins in the Tenno Sho (both spring and autumn) and Japan Cup. T M Opera O was inducted into the Japan Racing Association Hall of Fame in 2004.