Harold Alan Hamersley MC (6 February 1896 – December 1967) was an Australian World War I flying ace credited with 13 confirmed aerial victories.

[3] Following the outbreak of World War I, Hamersley volunteered for overseas service, joining the Australian Imperial Force on 18 February 1915.

[3] Listing his occupation as a farmer,[4] upon enlistment he was commissioned as a second lieutenant and assigned to the 16th Battalion, with whom he embarked as part of the 5th Reinforcements to leave Fremantle on board HMAT Hororata on 26 April 1915.

[5] He fought with the battalion in the Gallipoli Campaign and suffered a bullet wound to his right thigh in August and was evacuated to Cairo.

He returned to his unit in October and remained at the front until November when he contracted influenza and was evacuated to Mudros.

[4][6] Later that month he was promoted to lieutenant and in June 1916 was transferred to France[4] along with the rest of his battalion, to take part in the fighting in the trenches of the Western Front.

On the 22nd, he shared a victory as he helped Captain Robert L. Chidlaw-Roberts become an ace by driving down an Albatros D.III out of control.

He then became the Avro test pilot for a while; it was during this time that he set an altitude record in an aircraft powered by an Austin 7 motor.