Pierre-François Olivier de Vézin (also Vésin and Vézain) (28 April 1707 – April 20, 1776) was a Canadian ironmaster and chief surveyor of Louisiana sent by King Louis IV.
He served in the Cabildo as chief councilor and died in New Orleans April 20, 1776.
His family coat of arms hangs in the Cabildo today.
He married Marie-Joseph Duplessis, daughter of Jean-Baptiste Gastineau Duplessis.
His children, grandchildren, many generations were established, well known in New Orleans.
Some include Gerard de Marigny de Mandaville, P.G.T.
Beauragaurd, C.C.
Claiborne, Francois -Marie Chevalier di Reggio, and many more.
Pierre-François' daughter Victore-Francios, became mother superior at Ursulines Convent and led prayers in the streets in the Battle of New Orleans.
She is responsible for the veneration of Our Lady of Prompt Succor mass at Thanksgiving that is still celebrated on January 8 annually.