Black.
Black is the color/colour of objects that do not reflect light in any part of the visible spectrum. Scientifically, a black object absorbs all the colors/colours of the visible spectrum and reflects none of them. This is sometimes confused with black being called "a mixture of all colors/colours", but that is not the case. In fact, an object emitting or reflecting all colors/colours is perceived as white, although in terms of paint, inks and other pigments, mixing pigments of all colors/colours will eventually form black as eventually a mixture which absorbs all the light and thus appears black forms. Sometimes black is described as an "achromatic color/colour"; in practice, black can be considered a color/colour, e.g., the black cat or black paint.