William Bachrach (May 15, 1879 in Chicago, Illinois – July 1959) was an American swimming and water polo coach.

[5][7][8] Imposing and somewhat demanding as a coach, the 6 foot tall Bachrach weighed 300 pounds in later life, though his students enjoyed and welcomed his guidance, referring to him as “the beloved tyrant.”[5][6] He began as a swimming instructor at the Chicago Central YMCA.

[5][9] His 1914–17 IAC water polo teams won the U.S. national championship for four straight years.

[2][5] At the IAC, he coached Jam Handy, Harry Hebner, Mike McDermott, Perry McGillivray, Norman Ross, Bob Skelton, Johnny Weissmuller (later famous in Hollywood as "Tarzan"), Arne Borg, Sybil Bauer, Ethel Lackie, and others.

[5] He also developed Norman Ross, who won gold medals in the 400m and 1,500m freestyles and 800m relay at the 1920 Olympics in Antwerp.