Vincent Van Gogh - Head of a Skeleton with a Burning Cigarette, 1886

It's a student joke from Van Gogh's Antwerp days, and it still gets a grin. A skeleton sits in the dark with a lit cigarette clamped between its teeth, looking for all the world like it has just stepped out for a quiet smoke. Its jaw is set, its head is tipped slightly forward, and a thin trail of smoke drifts off to the right.

The paint is thick and loose, in bone whites, creamy yellows and soft olive greens, all set against a deep black background. A cheeky, slightly macabre picture from one of the best-known painters in the world.