Medardus or Medard was the Bishop of Noyon. He moved the seat of the diocese from Vermand to Noviomagus Veromanduorum in northern France. Medardus was one of the most honored bishops of his time, often depicted laughing, with his mouth wide open, and therefore he was invoked against toothache.

The former French Catholic Diocese of Noyon lay in the north-east of France, around Noyon. It was formed when Saint Medardus moved the seat of the bishopric at Vermandois to Noyon, in the sixth century. For four centuries it was united with the bishopric of Tournai as the Diocese of Noyon–Tournai. Then in the twelfth century it was again independent, and the bishop of Noyon became a pairie-comté of France.