The Aperture Science Robot Worker is a humanoid robot apparently introduced in the 1980s to replace some human workers in the Enrichment Center, as shown on various posters seen in Test Shaft 09 and the Turret Production Line in Portal 2.
Concept art a humanoid female face.
Concept art of humanoid robot.
Ditto, with captions.
Concept art of robots storing Sentry Turrets.
Concept art of incomplete humanoid robots placed in realistic positions in a Relaxation Chamber.
Propaganda poster for robots' Relaxation Vaults.
Humanoid robots being built by Aperture scientists.
"Bring Your Daughter to Work" poster, featuring a robot little girl.