(15788) 1993 SB is a trans-Neptunian object of the plutino class. Apart from Pluto, it was one of the first such objects discovered, and the first to have an orbit calculated well enough to receive a number. The discovery was made in 1993 at the La Palma Observatory with the Isaac Newton Telescope. Very little is known about the object. Even the diameter estimate of ~130 km is based on an assumed albedo of 0.09.