Thomas Grier DFC (1918 – 5 December 1941) was a British flying ace of the Royal Air Force (RAF) during the Second World War.

Born in Glasgow, Grier joined the RAF in mid-1938 and was undergoing flying training at the outbreak of the Second World War.

Later living in Stow-on-the-Wold in Gloucestershire, England, in May 1938, he applied to join the Royal Air Force (RAF) on a short service commission and was accepted for training.

Equipped with Hurricanes, it was engaged in convoy patrols along the English Channel and became drawn into the Battle of Britain as the Luftwaffe commenced its campaign against British shipping traversing these waters.

He shared in the destruction of a Junkers Ju 88 medium bomber near the Isle of Wight on 16 July and four days later assisted in the shooting down of a Heinkel He 59 floatplane to the south of Selsey Bill.

[2][5] On 18 August, now known as The Hardest Day, Grier destroyed a pair of Junkers Ju 87 dive bombers to the south of Selsey Bill.

[1][2] The citation, published in The London Gazette, read: This officer has taken part in a considerable number of engagements against the enemy and has destroyed eight of their aircraft as well as sharing in the destruction of others.

[2][4] Grier's substantive rank was made up to flight lieutenant in September and the next month he was promoted to acting squadron leader and given command of No.