Atlas (referred to as Blue by GLaDOS), is P-body's short and stout companion, and is one of two playable android Test Subjects built by GLaDOS for her Cooperative Testing Initiative, which was devised to phase out human testing.
Gameplay-wise, Atlas is played by the host of the Co-op session; the player that sends an invitation.
Atlas is a blue eyed Core with a basic design as a typical rounded Core, and is portrayed to have somewhat more masculinity in its programming than in P-body. GLaDOS had created the Cooperative Testing Initiative after her awakening in Portal 2, as a means of replacing Chell as her only Test Subject. Along with P-body, the two bots are pitted against a series of tests built by GLaDOS herself, utilizing the many different mechanics previously encountered by Chell from the game's single-player campaign.
It was later revealed by GLaDOS that Atlas and P-body's Cores are programmed specifically to do nothing more but tests.
During the final phases of testing, GLaDOS reveals that, while the Cooperative Testing Initiative has its uses, she needs human testing for science, not robots. GLaDOS reveals that there are humans locked away, deep within the ancient Aperture facilities. There the bots will be tasked with navigating the old test chambers and unlock the massive vault containing the humans, seemingly kept in place by some form of cryogenic storage. By doing this, they 'save science.' However, almost immediately after the robots unlock the room containing the test subjects, they are destroyed. They are eventually rebuilt and, during the credits, Atlas sits at a computer desk and watches P-body playing on a conveyor belt.
| Small Wave
|| Default gesture, available from the beginning.
|| This gesture makes Atlas wave his hand.
| High Five
|| Complete the Calibration Course
|| Can only be performed when Atlas is near P-body. If one of the bots decides to perform the High Five, the other one will do it too.
| Rock Paper Scissors
|| Complete the fourth chamber of the Team Building Course.
|| Can only be performed when Atlas is near P-body. If one of the bots decides to play a game of Rock Paper Scissors, the other one will take part in it too. Depending on the outcome, the bots will react to it by cheering or showing disappointment.
|| Complete the Team Building Course.
|| This gesture makes Atlas laugh and slap one of his legs.
| Robot Dance
|| Complete the fifth chamber of the Mass and Velocity Course.
|| This gesture makes Atlas perform a dance move called the 'Wave'.
| Team Tease
|| Complete the Mass and Velocity Course.
|| Can only be performed when Atlas is near P-body. In this gesture, Atlas takes the head part of P-body and places it on the ground while laughing. P-body will take his head back and smack Atlas with it.
| Team Hug
|| Complete the eighth chamber of the Hard Light Surfaces Course
|| Can only be performed when Atlas is near P-body. Self-explanatory.
| Trick Fire
|| Complete the fourth chamber of the Excursion Funnels Course.
|| This gesture shows how skillfully Atlas can shoot his Portal gun.
Development and Acting
Both Atlas and P-body are voiced by Dee Bradley Baker.
Atlas' first-person view.
Atlas' Primary-fire portal.
Atlas' Secondary-fire portal.
Both of Atlas' portals.
Blueprint of Atlas on a shirt.
Atlas on a poster with P-body
Pre-release screenshot of Atlas and P-Body.
Another pre-release screenshot of Atlas and P-Body.
Atlas while in a test chamber.
- In the pre-release video "Bot Trust", the prototype Atlas in the "Unilateral Force-Induced Isokinetic Breakfast Trials" wields a frying pan similiar to the ones found in Left 4 Dead 2, the frying pan is also featured in Team Fortress 2 as an all-class melee weapon, and in other Valve games (but as unusable physics props).
- In Portal 2 and it's promotional videos, Atlas' name can be seen written both as "Atlas" and "ATLAS", showing inconsistencies from Valve as far as the bot's name is concerned.
- In the early days of Portal 2, the player used to play as a different character, named Mel. She was later replaced by Atlas, with Chell being replaced by P-Body.
- Atlas made 2 cameos, along with P-body in LEGO Dimensions.
- Atlas is a Steam Exclusive character in the Good Friends DLC of the game Runner2