Charles Jean Marie Loyson (10 March 1827 – 9 February 1912), better known by his religious name Père Hyacinthe, was a famous French preacher and theologian.
He was a Roman Catholic priest who had been a Sulpician and a Dominican novice before becoming a Discalced Carmelite and provincial of his order, but left the Roman Catholic Church, in 1869, after major excommunication was pronounced against him.
He was known especially for his eloquent sermons at Notre Dame de Paris and sought to reconcile Catholicism with modern ideas.