Saint Cassian of Autun (French: Cassien) (died ca. 350 AD) was a 4th-century bishop of Autun. He may have been an Egyptian by birth. He traveled to Autun and was a follower of Saint Reticius, bishop of Autun. Cassian succeeded Reticius as bishop, serving for about twenty years, and was well liked by the people of his see. Gregory of Tours attributes miracles to Cassian. After the peace bought by Constantine he had a vision and decided to embark with some companions to evangelize the Britons. Getting as far as Autun, he became the assistant of Saint Rhétice Autun.