Seleucus Nicator (?-281 BC) was one of Alexander the Great's generals and the founder of the Seleucid kingdom in Persia.

At the time of Alexander's death in 323 BC Seleucus was the commander of the hypaspists, a unit of elite Macedonian troops in Alexander's army. While Antigonus, Ptolemy, Lysimachus, and Eumenes of Cardia were intriguing and battling over the remains of Alexander's empire, Seleucus was assigned the satrapy of Babylonia. In 315 BC, Antigonus siezed Babylon and expelled Seleucus, only to have Seleucus take back the city in 312 with the aid of Ptolemy.

Sometime after 311, Seleucus began to expand his domains, capturing Susiana and Media (modern Iran) from Antigonus and campaigning in the east against the Indian emperor Chandragupta Maurya. Eventually Chandragupta won out and in 303 BC, Seleucus made peace with the Indians, ceding Gandhara, Archosia, and Gedrosia to the Mauryan Empire in exchange for an Indian wife and 500 war elephants.

Nevertheless, Seleucus had now firmly established himself as a major player in Asia, and in 301 he joined in an alliance with Cassander and Lysimachus to defeat Antigonus and his son Demetrius at the Battle of Ipsus in Phrygia, in which Antigonus was killed. As his part of the spoils Seleucus took Syria, leaving him in control of all of Alexander's original empire except for eastern Afghanistan, Ptolemaic Egypt and Lysimachus' kingdom of Macedonia and western Asia Minor.

For the next 20 years Seleucus mantained an uneasy peace with the two rival kingdoms but finally in 282 ambition got the better of him and, now an old man, he invaded Asia Minor, defeating and killing Lysimachus at Corupedium. But then, as he was marching to capture Macedonia, Seleucus was betrayed and assassinated by his ally Ceraunus, who took the throne of Macedonia for himself.

Seleucus was succeeded as king of Persia and Asia minor by his son Antiochus I, and the Selucids would rule Persia for the next several hundred years. Of all of Alexander's generals, Seleucus was perhaps the most capable, and certainly came closest to reuniting the original empire. Seleucus was also an able administrator who adopted Persian customs and always tried to live up to Alexander's dreams of a harmonious cooperation between the Persian and Greek peoples.