Edmond Thieffry (French pronunciation: [ɛdmɔ̃ tjɛfʁi]; 28 September 1892 – 11 April 1929) was a Belgian First World War air ace and aviation pioneer.

Thieffry was born in Etterbeek, a municipality of Brussels, and went on to study law in Leuven (hence his nickname "The Flying Judge").

Using his legal knowledge and Dutch language skills he managed to talk his way out of internment, and travelled to Antwerp to rejoin the Belgian army.

[1] In 1915, Thieffry joined the Compagnie des Ouvriers et Aérostiers —the Belgian Army Air Corps— and with some difficulty qualified as a pilot at Étampes.

[citation needed] At the end of the war, Thieffry returned to Brussels by way of Switzerland, arriving home on 6 December 1918.

Sabena supplied a Handley Page W8f, which Thieffry named "Princesse Marie-José", after getting the support of his friend King Albert.

The flight plan called for stops at Marseille, Oran, Colomb-Bechar, Gao, Fort-Lamy, Bangui and Coquilhatville, and should have taken seven days.

During his second test flight in Congo on 11 April 1929, flying Aviméta 92, Thieffry, with fellow flyer Gaston Julien, was killed in a crash close to Lake Tanganyika (only a mechanic survived).