Heliodorus (minister)
According to the historian Appian, Heliodorus killed Seleucus while Seleucus’s oldest son Demetrius was a hostage in Rome and Seleucus’s second son Antiochus was too young to rule as king so Heliodorus could proclaim himself regent of the Seleucid Empire. Then Seleucus’s brother Antiochus overthrew Heliodorus and had him either exiled or killed and proclaimed himself King Antiochus IV.