Peter I of Alençon (c. 1251 – 6 April 1284) was the son of Louis IX of France and Margaret of Provence.

Back in France, he lived in Paris until 1269 when his father gave him in appanage the County of Alençon.

Following the death of his father in 1270, Louis IX, Peter's brother Philip became king of France.

[5] In December 1282, during the Sicilian Vespers, Peter marched his army to Naples to assist his uncle Charles I of Sicily, stopping at Reggio Calabria.

[6] His body was taken to Paris, where he was buried, with his heart interred at the now-demolished church of the Couvent des Jacobins.