Fabian Cortez is a fictional character in the Marvel Universe. He first appeared in X-Men (volume 2) #1 and was created by Chris Claremont and Jim Lee.

Cortez was part of the Acolytes, a sect of fanatical mutants who worshipped the immensely powerful mutant warlord Magneto as their deity (although Cortez was only using the Acolytes to further his own ends, and once manipulated Magneto against the X-Men and then tried to kill him), and lived on the space-station Avalon before relocating to the island nation of Genosha, which had been granted to Magneto by the United Nations. His ability was to enhance other mutants powers to extreme, and occasionally dangerous, limits. For example, if he enhanced a mutant whose powers were eye beams, like Cyclops, the beam could level a mountain, but the recoil would kill him.

Seeing as how Fabian Cortez had betrayed him earlier, Magneto had only let Fabian Cortez serve him on Genosha because his powers had been reduced and Cortez's mutant power was to highten the abilities of other mutants. After Magneto was restored to full power by one of the Genegineer's machines he no longe needed Cortez and pulled him from a prison in Hammer Bay fifty miles to Carrion Cove in less than 20 seconds. The impact killed Cortez instantly.