Shapur I (Middle Persian: 𐭱𐭧𐭯𐭥𐭧𐭥𐭩; New Persian: شاپور), also known as Shapur I the Great, was the second shahanshah (king of kings) of the Sasanian Empire. The dates of his reign are commonly given as AD 240/42 – 270/72, but it is likely that he also reigned as co-regent (together with his father) prior to his father's death in 242 (more probably than 240).