ATLAS is a robot from Portal 2, functioning as one of the two used during the co-op campaign, being controlled by Player One.
ATLAS is assembled and deassembled at the end of every stage in the co-op campaign, which is same case as P-Body. Both robots think they are simply completing tests, but as they continue throughout the campaign, it is learnt that they are being used by GlaDOS for her own plans. They eventually unlock a vault containing humans frozen in stasis, which grants them sincere praise from GlaDOS for the first time.
