Final answer:
The bishop overseeing Joan of Arc's trial was Pierre Cauchon, Bishop of Beauvais, who presided over the politically influenced proceedings in Rouen during the Hundred Years' War.
Step-by-step explanation:
The bishop who oversaw Joan of Arc's trial was Pierre Cauchon, the Bishop of Beauvais. Joan of Arc was captured by the Burgundians in 1430 and handed over to the English. The trial took place in Rouen and Pierre Cauchon, a loyalist to the English, presided over the proceedings due to his known animosity towards Joan and the French crown.
While the trial was ecclesiastical, it was largely influenced by political motivations aligned with English interests during the Hundred Years' War.