2003 EL 61
2003 EL 61 is an object beyond the orbit of Pluto with a semimajor axis of 43.31 AU and an estimated size of 2000 kilometers. The planetoid was nicknamed "Santa" by its discoverers and appears to have a satellite of its own; this was nicknamed "Rudolph".
The object is a rapidly spinning, elongated object roughly the size of Pluto. Its elliptical orbit could eventually bring it close enough to Neptune that it would get a gravitational yank into the inner Solar System. It would change from a dwarf planet to a short period comet.
2003 EL 61 completes a rotation once every 4 hours. It is likely the object collided with another Kuiper Belt Object some time in its early history, kicking it into a fast spin and elongating its shape. The satellites that surround the planetoid could be the debris left over from this impact.