Matfre Ermengau (died 1322) was a Franciscan friar, legist, and troubadour from Béziers. He had a master of laws (senhor de leis) degree.
He wrote one canso, whose melody survives, and one moralising sirventes. His most famous work was an Occitan poetic book in 35,600 octosyllables called the Breviari d'amor, begun in 1288. Encyclopedic in length and diversity, its sole purpose is the reconciliation of love for God with the erotic amours of the troubadour lyric. It is divided into parts and is structured like a "tree of love". The Breviari is preserved in twelve full codices and as many fragments. It was translated into Castilian and the Limousin dialect (once thought to be Catalan or catalanisant Occitan). Matfre also says that he would have written better in Latin (from which he borrowed the word breviari, from breviarium, not found elsewhere in medieval Occitan).
The work begins with popular theology, a section entitled "The Study of God and the Creation". From the Trinity it moves to angels, demons, then the zodiac and the planets. Then in a section entitled "The Study of Nature" ("Natural Law") he discusses the proper modes of worship, then the temptations that affect Christians and the sins they must avoid. Exempla are drawn from daily life. Finally, in "The Love of God", he summarises the Christian creeds, the life of Christ, and several hagiographies.