William Benjamin Chaffey (born in 1856 in Brockville, Ontario, died June 4, 1926 in Mildura, Victoria) was a Canadian engineer who with his brother George Chaffey developed what became the cities of Etiwanda, Ontario, and Upland in California, United States of America; and the city of Mildura, Victoria, Australia, as well as the town of Renmark, South Australia.
The Chaffey brothers carried out these developments between 1882 and 1896. In 1896 their Australian projects went bankrupt and George returned to the United States. William Benjamin (known as W.B.) remained in Mildura, however, becoming mayor in 1920 after the development had finally succeeded. Statues of Chaffey stand in Mildura and Renmark today.