Justin II or Justin the Younger (Latin: Iustinus; Greek: Ἰουστῖνος, translit. Ioustînos; died 5 October 578) was Eastern Roman Emperor from 565 until 578. He was the nephew of Justinian I and the husband of Sophia, the niece of the Empress Theodora, and was therefore a member of the Justinian dynasty.

Justin II inherited a greatly enlarged but overextended empire, with far less resources at his disposal compared to Justinian I. Despite this, he strived to match his formidable uncle's reputation by abandoning the payment of tributes to the Empire's neighbors. This miscalculated move resulted in rekindling of war with the Sassanid Empire, and in a Lombard invasion which cost the Romans much of their territory in Italy.