Joseph Cassani (also spelt Casani, 26 November 1673 – 1750) was a Spanish Catholic historian.
Cassani was born in Madrid in 1673, entered the Society of Jesus on 16 November 1686, was still in active service of priestly functions in 1745, and died in 1750.
He was one of the founders of the Academia de la Lengua española (Academy of the Spanish Language) at Madrid, and published a Diccionario de la Lengua Catellana (Catalan dictionary) there in 1726–1730, in six volumes.
Among his works may be noted Admirable vida, singulares virtudes etc.
The fact that Cassani was never in the New World detracts somewhat from the usefulness of this otherwise valuable history, as far as ethnologic and ethnographic data are concerned; but it does include data on the missions in the upper Orinoco basin.