Waldemar K. von Zedtwitz (May 8, 1896 - October 5, 1984) was a German-born American bridge player and administrator.
Von Zedtwitz was born in Berlin, Germany; his mother was from Kentucky and his father was of the minor nobility of Saxony. He was educated at Berlin and Bern, and later served in the German cavalry during World War I. He became a naturalized American citizen.
He was a lexicographer and linguist.
von Zedtwitz was a keen backgammon player, winning a major tournament at age 82. He lived for 47 years in New York City before relocating to Hawaii in 1977. He died in Hawaii in 1984.
He was friends with Harold Vanderbilt, the inventor of contract bridge, and became an early and enthusiastic competitor and promoter of the game, including a tour of Europe.
Von Zedtwitz was 1932 president of the American Bridge League, one of the organizations whose merger established the American Contract Bridge League in 1937. The ACBL credits him with saving it by his emergency service as president in 1948 and 1949. He was a founder of the World Bridge Federation.
Von Zedtwitz was named to its hall of fame by The Bridge World in 1966, which brought the number of members to nine. They were made founding members of the ACBL Hall of Fame in 1995.