GLaDOS (Aperture Science Genetic Life-form and Disc Operating System) is a robot appearing in both Portal games. She was originally Cave Johnson's assistant in the old days of Aperture, named Caroline. Cave wanted to be turned into a computer to run the facility, but he died before they could. He had stated that if he died before he could be turned into a computer, he would have Caroline run it. And that is exactly what happened. Later in the game, she gets turned into a potato battery. GLaDOS' model names are "models/npcs/glados/glados_animation" and "models/npcs/potatos/world_model/potatos_wmodel"

Wheatley (Aperture Science Intelligence Dampening Sphere) is a robot appearing only in Portal 2, although the Cake Core from Portal 1 does have a similar appearance to Wheatley. Wheatley was created to make GLaDOS less smart, and not kill the scientists. It generated an endless stream of terrible ideas inside GLaDOS' head, thus leading her to make bad decisions. Wheatley eventually becomes in charge of the facility, which leads to the building almost exploding. Wheatley's model names are "npc_personality_core" and "npc_wheatley_boss"

The Space Core (Aperture Science Space Sphere) is the first corrupted core from the final battle. He is obsessed with space, hinting to the game's ending. Wheatley said to Space Core, "NOBODY IS GOING TO SPACE, MATE!" But as we all know, that statement did not age well. Space Core's model name is "npc_personality_core"

The Adventure Core, or Rick (Aperture Science Adventure Sphere) is the second corrupted core from the final battle. He loves adventure, and is the smartest of the corrupt cores, as it appears that he knows what is going on, unlike the other two. Adventure Core's model name is "npc_personality_core"

The Fact Core (Aperture Science Complimentary Fact Sphere) is the third corrupted core from the final battle. He goes on and on about untrue facts that he claims are true. In the ending cut-scene, it appears he is the only one to not get sucked into space. Fact Core's model name is "npc_personality_core"

Cameras (Aperture Science Vital Testing Apparatus) are technically not robots themselves, but the game refers to it as an npc, so I guess they can be considered robots. Cameras are used by GLaDOS to monitor you while you are testing. They move as you move, watching everything you do. The Camera's model name is "npc_security_camera"

Atlas (Aperture Science Core Test Subject) is the blue robot in the Cooperative Testing Initiative. Atlas' Portal Gun has blue lines on it, and the portals it shoots are light blue and purple. Atlas' model name is "models/player/ballbot/ballbot"

P-Body (Aperture Science Turret Test Subject) is the orange robot in the Cooperative Testing Initiative. P-Body's Portal Gun has yellow lines on it, and the portals it shoots are yellow and red. P-Body's model name is "models/player/eggbot/eggbot"

Turrets (Aperture Science Sentry Turret) are obstacles that appear throughout both Portal games. They first appear in Chamber 16 of Portal 1. They try to kill you, and shoot lots and lots of bullets. The Turret's model name is "npc_portal_turret_floor"

Defective Turrets (Aperture Science Non-Functional Sentry Turret) are turrets who have no bullets. They appear to be regular turrets without the outer covering. They say that they are blind and claim that they are not defective. The Defective Turret's model name is "models/npcs/turret/turret_skeleton"

Backwards Turrets (Aperture Science Opposite-Sided Sentry Turret) is a turret with it's head turned to the side. It's guns are positioned backwards, and only appear in Wheatley's Test Chamber 75 as a defective turret. The Backwards Turret's model name is "models/npcs/turret/turret_backwards"

Crap Turrets (Aperture Science Dilapidated Sentry Turret) is a turret, but is old and destroyed with tape covering over certain places. It appears to be defective in Wheatley's Test Chamber 75, but doesn't react at all in GLaDOS' Test Chamber 6. The Crap Turret's model name is "npc_portal_turret_floor" just with the skin set to 1.

Frankenturrets (Aperture Science Walking Weighted Storage Cube) are a combination of two turrets and cube. They were made by Wheatley to walk onto buttons, but don't function that way. They also make strange growling noises. The Frankenturret's model name is "prop_monster_box"

Rocket Turrets (Aperture Science Rocket Sentry Turret) are turrets that have a sphere-like head and a unique looking body. They fire rockets, and are used to kill GLaDOS in the first Portal. The Rocket Turret's model name is "npc_rocket_turret"

Tripwire Turrets (Aperture Science Rocket Tripwire Turret) are unused entities left in Portal 2's files. They take on the appearance of a rocket turret, but don't act the same way. When you touch the blue line coming out of it's eye, it shoots a rocket. When it hits you, the blue line disappears followed by some unique sound effects. The Tripwire Turret's model name is "prop_rocket_tripwire"

Hover Turrets (Aperture Science Hover Turret) are unused robots inside of Portal 2. They were meant to be taken on the appearance of the Curiosity Core from Portal 1, but in the game they show up as an error. The Hover Turret's model name is "npc_hover_turret"

Opera Turrets (Aperture Science Singing Sentry Turret) are turrets that are much larger than regular turrets. They show up in GLaDOS' Test Chamber 11 and GLaDOS' Test Chamber 16. They also appear in the ending cut-scene, along with the giant Animal King Turret. The Opera Turret's model name is "models/npcs/turret/turretwife"