Guillaume Colles, called Boisguillaume, and more often, Boscguillaume, of the Colles de Boisguillaume family, was a recorder of the Trial, and a notary of the ecclesiastical court of Rouen.

As early as 1424 one sees the name of Guillaume Colles as the signature of a writ of excommunication. Boisguillaume is to be found as the notary of the inquisitorial trial of Jean Seguent, held by Jean Graverent between July and November, 1430.

In 1421, he is cited as curé of Nôtre Dame de la Ronde (a benefice at the disposition of the King of England), and he signed the act by which the members of the clergy of Rouen, assembled in the archbishop's chapel, declared vacant the benefices of their confrères who lived in the territory loyal to the Dauphin.

A further reference is made when the court of Rouen is ordered by Henry VI to make an inventory of his property. He was then cited as cure of Nôtre Dame near Bernay, "under sentence of excommunication, aggravated and further aggravated . . . obstinate and a bad example to our mother the Church." This sale of his property was ordered so that the money might be employed for the benefit of his absolution.

Guillaume Colles lived at Rouen in the parish of Saint Nicolas.
He was a witness at the Rehabilitation, and on December 18 1456, gave details on the work of the notaries, declaring that the Trial had been made at the expense of the English, recognizing the documents that were presented to him, and revealing the trickeries of Nicolas Loiseleur and Jean d'Estivet.