Willy Omer François Jean baron Coppens de Houthulst, DSO MC (6 July 1892 – 21 December 1986) was Belgium's leading fighter ace and the champion "balloon buster" of World War I.

In mid July, he transferred to the single seater fighter unit 1ère Escadrille de Chasse (1st Pursuit Squadron).

On that day he carried out his first attack on German observation balloons, as an aid to a ground assault by the Belgian Army.

A week later, using his usual tactics of close range fire, Coppens cut a balloon loose from its ties.

Between April and October 1918 he was credited with destroying 34 German observation balloons and three airplanes, nearly as many victories as Belgium's other five aces combined.

His royal blue plane with its insignia of a thistle sprig wearing a top hat became so well known that the Germans went to special pains to try to kill him.

On 3 August he shot down a balloon booby-trapped with explosives that when detonated from the ground narrowly missed killing him.

The flaming wreckage of the balloon "fell swift as doom on the watching [German] staff officers, killing many and injuring the rest".

For his wartime service he was knighted, becoming Willy Omer Francois Jean Coppens de Houthulst, for a forest in his squadron's operating area.

In the late 1960s he returned to Belgium and lived his last five years with fellow Belgian ace Jan Olieslagers's only daughter until his death in 1986.