Jean de Châtillon, de Castellione, de Castilliono, de Chasteillon, and better, Jean Hulot de Châtillon, (he is so designated in his opinion concerning Jeanne), was archdeacon of Evreux, and later canon. He is not to be confused with the Italian Jean de Castiglione who became Bishop of Coutances in 1444

He had long been at the University; in 1403, he was said to be master of arts and bachelor of theology, and he must have been the comrade of Pierre Cauchon and Jean Beaupère at Paris. In 1418 he took part in the council which ended the charter of liberties of the French church.

He was teaching at the University of Paris on the Faculty of Theology in 1428, at the same time as Pierre de Dyerée, Guillaume Erart, and Guillaume. Adelie. He was already living at Rouen and was a doctor of theology before the Trial, and enjoyed some influence with members of the English government. In 1433 he received a canonicate at the cathedral, vacant upon the death of Couppequesne, by virtue of letters of the King.

In 1437 he became as well archdeacon of Vexin-Normand. It is not known what relationship he was to Guillaume, Lord of Châtillon, who is said to have conquered Château Thierry for the English king in August, 1426.

It is not very probable that he was threatened by Pierre Cauchon and evicted from sessions of the Trial as Jean Massieu reported at the Rehabilitation proceedings.

Very zealous in the Trial, he seems to have contented himself with disapproving of certain captious questions put to the accused. It was he who was in charge of admonishing the Maid on May 2nd.