Black
I've heard that black is not a color. That black is the absence of color.
Yet black has a name, and therefore is.
Arwen mourning over Aragorn in Two Towers, Lord of the Rings.
Black is the absence of life. The color of the departed. The void of the unknown. The unanswered.
The absence of good.
Nazgul, Lord of the Rings
Black is a shadow cast from light. Lying in wait against substance. A false that clearly defines truth.

When I see absence, I experience presence. Black is mystery.