Pedro III may refer to:
- Pedro III of Aragon (1239–1285)
- Pedro III of KongoPedro III of KongoPedro III Nsimba Ntamba was a ruler of the Kingdom of Kongo during its tumultuous civil war period.King Pedro III was the elder brother of King Joāo II and one of many partisans of the House of Kinlaza. Since 1666, the two royal kandas or lineages of Kinlaza and Kimpanzu had been fighting bitterly...
- Pedro III of Portugal (1717–1786)