Age: about 19 in human years
Birthday: N/A
Race/Ethnicity: Fairy
Sexuality: "'Love' is just a chemical reaction, and I'm not foolish enough to fall for it"
Heart Jewel: White Onyx

Likes: Reading, being right, perfection,
Dislikes: Being called small or a runt, being proven wrong, Opal

​Onyx is the second youngest Nightmare Agent, and the second agent to arrive on Earth. He's frail and baby-faced, but don't let that fool you! What he lacks in physical strength, he more than makes up for in intellect. He takes his time with his work and is a bit of a perfectionist, but has a terrible temper, and its quite easy to get under his skin.

His Nightmares are perfectly obedient, however, they are terribly predictable and tend to be very weak compared to the other agents. Onyx is no baby, and he’ll crush anyone who dares underestimate him!