In the Marvel Comics universe, Cerebro (Spanish and Portuguese for "brain") is a device that the X-Men (in particular, their leader, Professor Charles Xavier) use to detect mutants. It was created by Xavier, and was later enhanced by Dr. Henry McCoy. The current version of Cerebro is called Cerebra, to be distinguished from the character of the same name. Cerebro first appeared in X-Men Volume 1 #7 (1964).
Using Cerebro can be extremely dangerous, and telepaths without well-trained, disciplined minds put themselves at great risk when attempting to use it. This is due to the psychic feedback that users experience when operating Cerebro. As the device greatly enhances natural psychic ability, users who are unprepared for the sheer enormity of this increased psychic input can be quickly and easily overwhelmed, resulting in insanity, coma, permanent brain damage or even death. The one exception has been Magneto, who has been said to have minor or latent telepathic abilities as well as experience amplifying his mental powers with mechanical devices of his own design. Kitty Pryde once upgraded Cerebro so that non-telepaths could use the device. This was during the time that Professor Xavier was with the Shi'ar and Rachel Summers had just left the team. Kitty was able to track Nightcrawler who became missing after a battle with Nimrod.
The only characters to use Cerebro on a frequent basis are Professor X, Phoenix, the White Queen, and the Stepford Cuckoos. However, Rachel Summers and Psylocke have also used it. After the device was upgraded to Cerebra, Cassandra Nova used it in order to exchange minds with Xavier. The Stepford Cuckoos once utilized the machine to amplify their combined ability, with only one of them directly connected to the machine, but all of them experiencing its interaction due to their psychic rapport. The strain of mentally halting a riot during Open Day killed Sophie, the Stepford Cuckoo who was hooked up to Cerebra. Sophie was both inexperienced at using Cerebro and was high on the mutant-enhancing drug "Kick"; it is uncertain if the strain of using the machine, the drug, or both were responsible for her death. The now remaining three Cuckoos demonstrated that they were capable of using Cerebra with relative ease in Phoenix: Endsong.
Some mutants have learned to shield themselves from Cerebro, usually via their own telepathic ability. Magneto can shield himself from the device through use of minimal telepathic powers; in the film series, he does so with a specially constructed helmet.
When the human-Sentinel gestalt Bastion stole Cerebro from the X-Mansion, Cerebro was hybridized with Bastion's programming via nanotechnology. The resulting entity, a self-aware form of Cerebro, created two minions, Cerebrites Alpha and Beta, through which it would act without exposing itself. It also used its Danger Room-derived records of the powers of the X-Men and the Brotherhood of Evil Mutants to create its own team of imposter "X-Men" whose members possessed the combined powers of specific members of each of the two teams. Cerebro's goal was to put human beings in stasis so that mutants could inherit the Earth, and to this end it hunted down a group of synthetic children called the Mannites who possessed vast psychic powers. It was destroyed by the X-Men, with the help of Professor X and the Mannite named Nina. More recently, following the example set by the X-Men films, Cerebro has been replaced by Cerebra (referred to as Cerebro's big sister), a machine the size of a small room in the basement of Xavier's School For Higher Learning. Though designed to resemble the movie version of Cerebro, Cerebra is much smaller than the films' version. It resembles a pod filled with a sparkling fog that condenses into representations of mental images.
In the films X-Men and X2: X-Men United, Cerebro is a massive device that fills a spherical room in the basement of Xavier's School. The helmet interface is similar to the version seen in the comics, although the bulk of Cerebro's machinery is contained in the surrounding walls. While in use, three-dimensional images of the minds scanned by the device appear around the user. Unlike the comics' version of Cerebro, the film version can detect both human and mutant minds with ease. The unique signature of mutant brainwaves is shown in the first film by having human mental images portrayed in black and white, while those of mutants show up in color; In X2, mutants appear in red, and humans in white.
The only person seen using Cerebro successfully in the films is Xavier; Jean Grey attempted to use the device to locate Magneto, but the input overwhelmed her nascent telepathic power and left her stunned, though she was successful. It is mentioned that Magneto helped Charles Xavier design Cerebro. This has not been confirmed to be true in the comics, although the Magneto of the comics can use Cerebro and has designed similar devices.
In X2: X-Men United, the device was copied and modified by William Stryker in his plot to have a brainwashed Xavier use his Cerebro-amplified powers to kill the world's mutants, and was later further modified by Magneto to kill humans. According to X2, it is difficult to pinpoint the location of mutants who have the ability to teleport and are constantly in transit, such as Nightcrawler.
In the animated series X-Men: Evolution, Cerebro was shown being used by Jean Grey to amplify her telepathic and telekinetic powers in order to battle a possessed Professor X. This was the first time that Cerebro demonstrated the ability to process telekinetic ability; it is unknown if it possesses the ability to do so in the comics. Although originally appearing as a computer console with custom peripherals, this model was destroyed when Juggernaut attacked the X-Mansion. When rebuilt, it adopted a look almost identical to that of the movie.
In the 1996 Generation X telefilm on FOX, Cerebro was depicted as a desktop personal computer with a few custom peripherals. The scaled down depiction fit with the very low budget appearance of the movie in general.
In the 2008 series, Wolverine and the X-Men, Cerebro is damaged is the unexplained attack on Professor X. With Warren Worthington's money and Forge's technical expertise, they were able to get Cerebro repaired. Emma Frost used Cerebro to locate Xavier in Genosha.
In the video game X-Men Legends, Cerebro is identical to its appearance and usage in the X-Men film. Jean Grey and Emma Frost use the device at one point to attempt to return Professor X's mind to his body. In X-Men Legends II: Rise of Apocalypse, it was destroyed along with the rest of the mansion, but Forge mentioned plans on building Cerebra to replace it.
In the universe of Marvel Zombies, zombified versions of Beast and Mr. Fantastic reprogram Cerebro to help them and the other zombies track down the last remaining humans on Earth. Cerebro locates many in the European nation of Latveria, but all escape.