| Character Name: | Onyxx |
| Publisher: | Marvel Comics |
| Debut: | X-Men, vol. 2 #171 (August 2005) |
| Creators: | Peter Milligan (writer) Salvador Larroca (artist) |
| Full Name: | Sidney Green |
| Species: | Human Mutant |
| Alliances: | Chevaliers training squad Xavier Institute X-Men in training |
| Powers: | Superhuman strength and durability |
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] He develops a crush on fellow student Foxx, who is later revealed to be a disguised Mystique.[3]
Sidney is one of 198 mutants who retain their powers after the Scarlet Witch depowers most mutants on M-Day.[4] [5] [6] [7] He is later killed by Wither before being resurrected after the establishment of Krakoa.[8] [9]
Onyxx has a craggy granite body, which gives him superhuman strength and durability. He also possesses an additional pair of eyes, but it is unknown if these serve any special purpose.