William "Bill" August Kooistra (August 26, 1926 – March 30, 1995) was an American water polo player who competed in the 1952 Summer Olympics and in the 1956 Summer Olympics.
He was born in Chicago and is the older brother of Sam Kooistra.
Kooistra was a member of the American water polo team which finished fourth in the 1952 tournament.
In 1976, he was inducted into the USA Water Polo Hall of Fame.
This biographical article relating to a water polo figure from the United States is a stub.