Seleucus III Soter, called Seleucus Ceraunus (Greek: Σέλευκος Γ΄ ὁ Σωτήρ, ὁ Κεραυνός, Séleukos ho Sōtḗr ho Keraunós; c. 243 BC – April/June 223 BC, ruled December 225 – April/June 223 BC),[1] was a ruler of the Hellenistic Seleucid Kingdom, the eldest son of Seleucus II Callinicus and Laodice II.

Alexander changed his name to Seleucus after he succeeded his father as King.

Seleucus's rule was troubled & unstable, during his tenure he unsuccessfully continued his father's war in Asia Minor against Attalus I of Pergamon.

However he lacked character & was usually very sickly, making him mostly unable to fulfil his ambitious ideas.

After a brief reign of less than two years (225–223 BC), he was assassinated in Anatolia by members of his army, possibly at the instigation of his powerful minister Hermeias.