A fine representation of Seleucid troops from a Russian journal as I can recall. Kudos to the creators. As I can see, from left to right there are a Seleucid Elite trooper

(possibly Argyraspis or Chalkaspis), a thyreophoros, a pezhetairos (phalangite pikeman) and an armoured driver/trooper of a war chariot.

The Seleucid Empire (officially a kingdom because the term ‘Empire’/Imperium was not yet in use) was the largest Hellenistic state in area and population among the states that came from the dissolution of Alexander the Great’s Empire for the whole of the Hellenistic Period excluding its last century (1st c. BC). But it was the most potent Greek state only during the 2nd c. BC.

Below, a map of the Seleucid Empire 281 BC on the eve of the murder of its founfer Seleukos Nikator (credt: wikimedia commons).