Starmen are enemies in Mother and EarthBound, and have many different variants. They are Giygas's main henchmen, and because of this, are very iconic enemies of the series.
Starmen in Mother are very common, first appearing in Spookane's hotel as a boss, disguised as a hotel worker, and becomes a regular enemy from that point on.
Starmen in EarthBound comparatively do not appear in their regular form as much as they do in Mother, only appearing in Stonehenge base. There are many other variants, however.
"The Starman often warps into the middle of the party to attack. This robot is the primary sentry in the Stonehenge base. Watch out for his beam weapon and PSI magnet attacks."