John Frederick Mann (1819 – 7 September 1907) was an Australian surveyor, remembered for his accounts of Ludwig Leichhardt's second expedition.
December 1846 – May 1847 he was second in command of Leichhardt's second expedition (Darling Downs to West Australia) in the party of nine: Leichhardt, Mann, James Perry (saddler), Heinrich Boecking (tanner and baker)[a] Henry Turnbull, Hovenden Hely, Daniel Bunce (botanist), and two Aboriginals: Harry Brown and Jemmy Wommai or Wamai.
The expedition was abandoned at Peak Range (near present-day Emerald) after sickness overcame much of the party.
He was an authority on matters relating to the early history the colony and the aboriginals.
Mann died, aged 88 years, in Neutral Bay, Sydney.