Bartol Kašić (Latin: Bartholomaeus Cassius, Italian: Bartolomeo Cassio; August 15, 1575 – December 28, 1650) was a Jesuit clergyman and grammarian during the Counter-Reformation, who wrote the first Illyrian grammar and translated the Bible and the Roman Rite into Illyrian (a name used for early Croatian or proto-Serbo-Croatian).