Toutatis:

In 1989, asteroid 4179 was discovered by French astronomers and named Toutatis after a Celtic god that was the protector of the tribe in ancient Gaul. Its eccentric, four-year orbit extends from just inside Earth's orbit to the main asteroid belt.

In December 1992, Toutatis made a close approach to Earth. At the time, it was an average of about 4 million kilometers from Earth. Images of Toutatis were acquired using radar carried out at the Goldstone Deep Space Communications Complex in California's Mojave desert. The radar images of Toutatis reveal two irregularly shaped, cratered objects about 4 and 2.5 kilometers in average diameter which are probably in contact with each other. These "contact binaries" may be fairly common since another one, 4769 Castalia, was observed in 1989 when it passed near the Earth. Numerous surface features on Toutatis, including a pair of half-mile-wide craters, side by side, and a series of three prominent ridges -- a type of asteroid mountain range -- are presumed to result from a complex history of impacts.

Toutatis is one of the strangest objects in the solar system, with a highly irregular shape and an extraordinarily complex tumbling rotation. Both its shape and rotation are thought to be the outcome of a history of violent collisions. One consequence of this strange rotation is that Toutatis does not have a fixed north pole like the Earth. Instead, its north pole wanders along a curve on the asteroid about every 5.4 days. The rotations of hundreds of asteroids have been studied with optical telescopes. The vast majority of them appear to be in simple rotation with a fixed pole and periods typically between one hour and one day, the scientists said, even though the violent collisions these objects are thought to have experienced would mean that every one of them, at some time in the past, should have been tumbling like Toutatis.