Cerebro is a machine designed by Professor Charles Xavier for the purpose of locating mutant human beings possessing superhuman abilities. Cerebro does so by detecting the unusual waves of psionic energy ("brain waves") which superhumanly powerful mutants emit for reasons and through processes which remain unknown. The computer system in Cerebro can roughly measure the amount of superhuman power possessed by the mutant, determine the mutants geographical location, and even specify the identity of the mutantsif given sufficient data.

Although anyone can be taught to use it, Cerebro acts most effectively when it is linked to the mind of Professor Xavier or a being with similar telepathic abilities. By wearing a special headset connect to Cerebro, Xavier is able to use his psionic powers to increase Cerebro's ability to detect prionic waves. Indivdual members of the X-Men have sometimes carried smaller versions of Cerebro colloquially termed "portable Cerebros" with them. A "portable Cerebro" in telemetric with the main computer console, can detect the presence of a human mutant at short range.

Xavier began work on developing Cerebro before he founded the X-Men. He used an early version of the device, he called Cyberno to locate Scott Summers, who, as Cyclops, became Xavier's first recruit for the X-Men. Xavier completed the first true Cerebro machine shortly after the fifth X-Man, Marvel Girl (now known as Phoenix II), joined the team. He named Cerebro after the human cerebrum, the largest section of the human brain and the part responsible for transmitting waves.