César de Bus was a 16th-century French Catholic priest who established two religious congregations. Born in Cavaillon in 1544, he initially served in the king's army during the wars against the Huguenots. After a period of worldly pursuits in Paris, he returned to a religious life and was ordained in 1582. He became widely recognized for his dedication to preaching and teaching the Christian faith, eventually founding groups dedicated to spreading religious doctrine through instruction.