What planet was discovered in 1801 and reclassified several times before finally ending up being called a Dwarf Planet in 2006?

Ceres was discovered by Giuseppe Piazzi at Palermo on January 1, 1801. It was, for many years, classified as the fifth planet. However, in the 1850's scientists discovered other smaller objects in the same orbital area as Ceres, and reclassified it as a new type of object which they called an asteroid (meaning: Little Star, since that is how those objects appeared to the primitive telescopes at the time). This drama would play out again for a different planetary object in 2006.

What led to Ceres's second reclassification? Since its discovery, Pluto had been regarded as a planet. But with the discovery of objects in the Kuiper Belt in the 1990's, history would repeat itself. Pluto wasn't alone in its area of space. Many astronomers wanted to demote its status. But many wanted it to stay also. But then the question came up - Pluto is in the Kuiper Belt. If Pluto was a planet, why wasn't Ceres a planet? This was debated hotly, and in the end, they came up with a new type of planet - the "Dwarf Planet", and reclassified both Pluto and Ceres as dwarf planets (along with several other dwarf planets in the Kuiper Belt).