- Serah: "An arm!?"
- Noel: "Yeah, and not looking to shake hands, I'm guessing..."
- —Paradox Alpha attacks Serah, Mog, and Noel after their arrival at the Ruins.
Atlas's fragment entry is gained after defeating it as a boss.
- Atlas is a giant war machine that was excavated from the Bresha Ruins. The technology appears to be of human origin, rather than fal'Cie. This suggests that it is a relic from a future civilization.
- The machine can be operated through its crystal-controlled AI and sensory perception apparatus. Academy scientists hypothesize that the machine was built to combat large-scale fal'Cie, but stress that their research is still in the early stages.
Atlases are inventions of the Academy created during a war caused by a debate over bringing the Cocoon fal'Cie back as means of power: one group sees this as the best way to save Cocoon, while the other sees this as a repeat of history. Created in the war's climax, the Atlases become too strong for humans to control, attacking everything and everyone around them. Noel Kreiss sees this event to be the cause of Cocoon's fall.
By events not completely revealed, an Atlas ends up in the Bresha Ruins in Cocoon at 5 AF. It attacks Serah and Noel when the protagonists first arrive using its left arm, labeled "Paradox Alpha", while the rest of its body is invisible due to it being in another time-space. The battle ends once the Academy's PSICOM enforcers arrive and drive the giant off with their airships' fire power.
As Atlas's presence will shut down the site in the Bresha Ruins and hinder their search for a Time Gate, Noel offers to stop the giant and sets off with Serah to find it while Alyssa Zaidelle gives them information via radio. The Paradox Alpha attacks Noel and Serah along the way, and soon Noel discovers Atlas has completely phased into reality.
He and Serah learn from Alyssa that an energy surge was detected within the ruins and that a mysterious device has appeared. Serah asks if the device appeared with Atlas, and she figures that if Atlas is a weapon built by humans, they must have designed a way to stop it. Noel states the machine's appearance is no coincidence, and offers the choice of either finding the device that controls Atlas or facing it head-on.
If Noel and Serah face Atlas head-on, the paradox ending, "A Giant Mistake", is triggered. In this ending, Noel and Serah arrive in the time period where Gran Pulse is ravaged by the Atlases. They attempt to destroy them and prevent the end of the world. Serah vows to protect the future along with Noel, and they engage the Atlas army, determined to defeat it.
If Serah and Noel use the device in the ruins to weaken Atlas, they are able to defeat it, thus correcting the paradox affecting the Bresha Ruins.
In the "Blitz Squadron Chronicles" series of fragment entries it is revealed that in 9 AF, Blitz Squadron was given orders to apprehend an anti-government group basing its operations out of the Pulse frontier lands. The mission was a success, and at the group's base they discovered evidence of terrorists having obtained data on Atlas, and were attempting to build their own mega-soldier. This incident sparked a heated debate among the members of the Academy, one faction insisting that they delete all Atlas data files to prevent future misuse, while another claiming that the construction of the weapon was a necessary evil. If Atlas was indeed a future weapon, someone must build it or history would face another paradox. With no conclusion forthcoming, the data files were stored within Academy headquarters.
Paradox Alpha and Atlas are fought in the Bresha Ruins 005 AF.
Atlas is associated with two musical themes: "Worlds Collide" and "Giant Impact", which are both composed by Naoshi Mizuta. "Worlds Collide" plays during Noel and Serah's fight against Paradox Alpha, while "Giant Impact" plays during their fight against Atlas in its true form.
- Main article: Atlas (Airborne Brigade)
Atlas appeared in Final Fantasy Airborne Brigade some time around second half on February 2012 during an event called "FFXIII-2 Incursion from Valhalla".
- Main article: Atlas#Etymology
- The model for Atlas is a modified model of the fal'Cie Titan designed after an Iron Giant.
- Even though Atlas can be defeated at its full power in the demo (done through extreme grinding), the cutscene that plays after its defeat doesn't change.
- In the "Adamantite Ring" fragment entry it is said the controller for Atlas reads human thoughts and transforms them into physical action by telepathy.