Air vice-marshal Sir Francis John Williamson Mellersh, KBE, AFC (22 September 1898 – 25 May 1955) was a Royal Naval Air Service aviator and flying ace credited with five aerial victories during the First World War, and a senior commander in the Royal Air Force during the 1940s and 1950s. He was killed in a helicopter accident in 1955.

Mellersh joined the Royal Naval Air Service in 1916. He trained as a fighter pilot and was posted to 9 Naval Squadron in 1917. While flying a Sopwith Triplane on 28 July 1917, he drove down an Aviatik C. He switched to flying a Sopwith Camel and scored victories 15 October 1917 and 12 April 1918; the latter win was shared with squadron-mate Roy Brown. On 21 April 1918, Mellersh was a flight commander involved in the dogfight that brought down the Red Baron, Manfred von Richthofen; Mellersh claimed a Fokker Dr.I triplane destroyed on that date. His last victory came two days later.^[1]

Mellersh debarked from a helicopter onto a quay on 25 May 1955; he had been invited to cruise on a yacht belonging to the Itchenor Yacht Club. As the helicopter departed, one of its rotors hit the mast of a yacht. As the copter crashed, the main rotor killed Mellersh.^[2]