Guillaume Cammas (1688–1777) was a French painter and architect.
Cammas was born in Aignes, Haute-Garonne, Midi-Pyrénées. He studied under the painter Antoine Rivalz, and designed the façade of the Capitole de Toulouse, built between 1750 and 1759. He was one of the founders of Académie royale de peinture de Toulouse, where he taught. His son François-Lambert Cammas designed the transept of the église Saint-Pierre des Chartreux de Toulouse.