10 Most Interesting X-Men You've Never Heard Of
9. Marrow
Marrow was a member of the underground community of Morlocks and was one of the few to survive Mister Sinister's attempts to wipe them out. Afterwards, she was taken in by the Morlock's leader Callisto, who became like a mother to her.
Sarah has the ability to enhance her skeletal structure, able to cover herself with bone armour or fashion it into spikes. Initially, her powers caused her a great deal of pain. This contributed to her already angry personality and led to her joining the mutant terrorist group Gene Nation.
She would later reform though. When Callisto was injured, Marrow took her to the X-Men for help and ended up joining the team. While on the Skrull homeworld, a medical device gave Sarah greater control over her powers, allowing her to become less monstrous-looking, which in turn softened her personality.
Marrow later left the X-Men to strike out on her own and disappeared for a while. She appeared sporadically afterwards, including when Scarlet Witch depowered 90% of all mutants. Sarah lost her powers, even though her bony protrusions remained.
She later regained her powers though, after allowing the evil scientist Volga to experiment on her. The experiment was a success, but Volga left Marrow for dead afterwards. She then joined a new version of X-Force to take him down.