Seleucus I Nicator (Nicator, "the Victor") (around 358-281 BC) was one of Alexander the Great's generals who, after Alexander's death in 323 BC, established himself and his family in Mesopotamia and the Iranian plateau, ruling as far as the Indus region. He founded Seleucia on the Tigris River (around 305) as a new royal capital.

Seleucid rulers