Seleucus I Nicator

Seleucus commanded elite infantry under Alexander and backed the first regent after the king's death in 323 BC, earning a post at Babylon. Within two years he'd joined a conspiracy that killed that same regent in Egypt. Rewarded with Babylon as satrap in 321 BC, he was almost immediately forced to flee by Antigonus, one of the most powerful successors. He returned in 312 BC with Ptolemy's help and spent the next decade expanding east, seizing the Persian and Median lands. His claim to northwest India brought war with Chandragupta Maurya; the peace treaty in 303 BC cost him territory but gained him 500 war elephants, which he used to crush Antigonus at Ipsus in 301 BC. After defeating Lysimachus in 281 BC and adding Asia Minor, Seleucus crossed into Thrace with designs on Macedon itself - and was assassinated by a refugee he'd sheltered at court, ending the westward dream but leaving his son an empire that would dominate the Hellenistic east for generations.