The black velvet is a cocktail made from Guinness Stout and a white, sparkling wine, traditionally Champagne.
A black velvet is made by filling a tall flute glass halfway full of chilled Guinness, and floating the sparkling wine on top of the Guinness; the differing densities of the liquids causes them to remain in separate layers.
In place of Champagne, apple or pear hard cider is sometimes used. Whatever the mixer, the effect is best achieved if it is poured over a spoon turned upside down over the top of the glass, so it runs down the sides rather than mixing with the Guinness.
A similar effect is achieved by mixing Guinness and a light-colored beer in the black and tan cocktail.
Black velvet is also velvet that is colored black. Black velvet is frequently used as a medium for paintings. It is the traditional vehicle for painted portraits of Elvis Presley, and for many other subjects meant to be seen under the light of a black light bulb.