The Savage Land Mutates are a team of mutated villains created by Magneto. They are based in the Savage Land and initially referred to themselves as the Beast-Brood.
Early in his supervillain career, the mutant Magneto created a headquarters in the Savage Land, a tropical jungle existing within Antarctica. Finding mutations that occurred easily in this land due to high levels of radiation, Magneto assembled various natives from tribes all over the Savage Land and, calling himself "the Creator," subjected them to experiments that greatly enhanced their physiology, creating the Savage Land Mutates.
When the superhero team of mutants, the X-Men, were exploring the Savage Land, the Mutates battled the X-Men and X-ally, the Savage Land protector known as Ka-zar. Revealing the Creator as Magneto, the X-Men were captured until Jean Grey ultimately destroyed Magneto's headquarters and machines, burying Magneto under the debris and reverting the mutates back to their non-superhuman state.
For reasons that remain unknown, the Mutates reverted to their superhuman forms and captured scientists hoping to create other Mutates. The superhero team of Avengers with their Asgardian ally, Sif, searched for the scientists and defeated the Mutates, who were remanded to the custody of the nearest legal authorities, in Chile.
Later, Magneto and the Mutate known as Piper captured several of the X-Men and the Avengers, before escaping capture when the Avenger Vision turned the tables on them.
The Angel and his ally, Spider-Man, later traveled to the Savage Land, searching for Karl Lykos, also known as the pterodon/villain Sauron. They, along with Ka-Zar, encountered and were captured by some of the Savage Land Mutates (Gaza, Barbarus, Vertigo, Amphibius and Brainchild, who had learned to use Magneto's machines for his own purposes.) Lycos managed to rescue his friends, but doing so freed his evil alter-ego of Sauron, who joined with Savage Land denizen Zaladane in leading the Mutates. The X-Men arrived to defeat the Mutates and free their friends, reverting Sauron to Lycos and the Mutates to their non-superhuman state once more.
Apparently, the effect of the mutation-inducing technology that gave the Savage Land Mutates their powers causes them to eventually regain their superhuman forms should they lose them, since the Mutates, with their leader, Zaladane, encountered and fought the villain known as the High Evolutionary.
Afterwards, Zaladane led the Mutates in kidnapping scientists, raiding Antarctic stations, and plundering Chilean cities, engaging in war-like acts across the Savage Land. Later, she made the Mutates kidnap the X-Man Polaris and succeeded in stealing her powers, which led the X-Men to battle the Mutates to rescue her.
Soon after, Zaladane tried to merge with the south magnetic pole to gain even more power. Investigating, Magneto, the X-man, Rogue, Ka-Zar, and the espionage orgainzatin SHIELD encountered the Mutates and an army of prisoners led by the Mutate, Worm. Magneto succeeded in killing Zaladane, and the heroes destroyed the Mutates' headquarters.
Later, the X-Men, Wolverine, Rogue, and Jubilee, traveled to the Savage Land in order to find traces of Magneto. Instead, they discovered that Sauron had taken charge of the Savage Land Mutates again, as well as uniting the variant Savage Land tribes. The two Mutates and X-Men fought, but after triumphing, the heroes chose not to reverse Sauron to Karl Lycos.
Sauron, however, eventually needed more and more energy, and sought the X-man Havok, since it was touching Havok that created Sauron in the first place. The Mutates Worm and Whiteout kidnapped Havok, which led other X-Men, Cyclops, Jean Grey and Polaris, to follow. After a series of battles, Phoenix was finally able to defeat their foes by reducing Sauron to a mindless creature and escaping the Savage Land.
Recently, the team faced the New Mutants.