William Jackson Brack (June 17, 1837 – April 30, 1901) was the first mayor of Orlando, Florida from 1875 to 1877. He served in the Florida House of Representatives from Brevard County from 1885 to 1887. He was born to John and Eliza (McCall) Brack in Georgia on June 17, 1837. He married firstly to the former Olive Chancey (1838–1864) of Clinch County, Georgia, by whom he had two sons who died young. The Bracks removed to Alexandria, Louisiana before the outbreak of the American Civil War. During that conflict, the future mayor served in Company C of the 27th Louisiana Infantry Regiment.