The Savage Land Mutates are a team of villains made by Magneto based in the Savage Land. Brainchild often uses his immense intellect to overcome the X-Men, even using mind control to make them fight themselves as he tries to conquer the Savage Land for himself. However, when the entire Savage Land and all its tribes come under threat he joins forces with Bishop, Nightcrawler, Psylocke and X-23. He tells Nightcrawler how to teleport the entire tribe to safety, away from an aerial bombing of their position. He also helps the X-men regain Marvel Girl from the mind control she's suffering from, as she was being forced to make Storm create a storm that would encompass the world, giving domination to the Savage Land Mutates.
Brainchild was created by Roy Thomas and Neal Adams in 1969 and first appeared in X-Men # 62.
What If ...
Brainchild appears in What If... Cable Had Destroyed The X-Men? and What If... Magneto Took Over The USA?