Onyxx

Onyxx (Sidney Green) is a fictional mutant appearing in comic books published by Marvel Comics. He first appeared in X-Men, vol. 2 #171 (August 2005), and was created by Peter Milligan and Salvador Larroca.

As a child, Sidney Green lived in various foster homes and orphanages, unable to find acceptance because of his crude behavior and chronic bedwetting.^[1] This was cured after his mutant abilities activated, transforming him into a four-eyed golem-like creature.

Subsequently, Sidney becomes a student at the Xavier Institute as Onyxx and joins Gambit's training squad, the Chevaliers.^[2][3] He develops a crush on fellow student Foxx, who is later revealed to be a disguised Mystique.^[4]

Sidney is one of 198 mutants who retain their powers after the Scarlet Witch depowers most mutants on M-Day.^[5][6][7][8] He is killed by Wither during the Necrosha event, but is later resurrected following the establishment of Krakoa as a mutant nation.^{[9][10][11][12][13][14]}

Onyxx has a craggy granite body, which gives him superhuman strength and durability.