Bertha Louise Townsend Toulmin (neTownsend; March 7, 1869 - May 12, 1909) was a female tennis player from the United States. She is best remembered for being the first repeating women's singles champion at the U.S. Championships (now: U.S. Open) (1888 and 1889). She discovered the under-hand technique.
She was inducted into the International Tennis Hall of Fame in 1974.