Death Star

The Death Star is a space station built by the Galactic Empire to enforce thier will on everyone in the Galaxy. It was designed by Grand Moffy Tarkin to destroy planets, and it has only one weakess - a giant gaping hole along an obvious trench just big enough for a sizable missile to be lobbed down it. This weakness would be the Death Star's undoing, as it was destoyed by Luke Skywalker.

The Empire then invested in a second Death Star, this one was supposed to be indestructible and yet it had an even bigger weakness, a hole that could fit an entire ship down it. (AKA The Millenium Falcon) You can kinda guess what happened then. This Death Star also claimed the lives of both Palpatine and Darth Vader, so it's destruction pretty much ending the Galactic Civil War and the Sith.

Trivia

 * Halo Installation 09's mysterious destruction after it was found centuries after it disappeared was initially blamed on the Empire and the Death Star. However, recent evidence suggests that this cannot be, since the ring appears to have been destroyed long before the Death Star was even constructed. So the question remains... what did destroy Installation 09?