Rainier[a] (died 16 September 1225) was an Italian cleric who served as the vice-chancellor of the Roman church from 1216 until 1219 and the Latin patriarch of Antioch from 1219 until his death.
He is described by Pope Honorius III as a "man of knowledge" (virum scientia) and a document of 1215 may indicate that he had a university degree.
[2] Before becoming vice-chancellor, Rainier was the prior of the basilica of San Frediano in Lucca, a community of canons regular.
[4] At Antioch, Rainier quarrelled with Prince Bohemond IV, who was confiscating church properties to make up shortfalls of cash.
Bohemond IV's son Philip had been married to Queen Isabella, but in 1224 he was imprisoned by Constantine of Baberon and the following year he died.