Castelmayran (French pronunciation: [kastɛlmɛʁɑ̃]; Occitan: Castèlmairan) is a commune in the Tarn-et-Garonne department in the Occitanie region in southern France.

[3] In the 12th century, the lordship belonged to a branch of the family of Argombat which founded the Cistercian abbey of Belleperche.

And by 1143 the final transfer of the abbey was discussed at a meeting held in Castelmayran.

[4] Castelmayran had several co-seigneurs over time[n 1], among whose Nicolas de Gourgues, the last one before the French Revolution.

[4] Before 1789, Castelmayran was a city of Gascony, in the diocese of Lectoure, and election of Lomagne.