The imperial Death Star is a space station capable of destroying entire planets. Its enormous firepower is unprecedented in the Star Wars universe and serves as the biggest threat to the Rebels and their fight against the Empire.
The First Death Star
The First Death Star was destroyed by Luke Skywalker
when he flew his X-Wing
into the death star's conveniently placed trench and fired two proton torpedo's into the death stars thermal exhaust port, but not without the help of Obi-Wan
The Second Death Star
The Second Death Star was built above the forest moon of Endor where a shield generator protecting the under construction station needed to be destroyed before Lando Calrissian and the rebel fleet flew into the unfinished superstructure and destroyed the hyper matter reactor core. The destruction of this battle station was the first step in the fall of the Empire. The difference in size between this station and the previous Death Star is considerable, and it essentially dwarfs any other construction in the entire Star Wars universe.