Death Star I

The Death Star I, also known as the first Death Star or simply the Death Star, was the Galactic Empire's ultimate weapon.
The Death Star was the code name of an unspeakably powerful and horrific weapon developed by the Empire. The immense space station carried a weapon capable of destroying entire planets. The Death Star was to be an instrument of terror, meant to cow treasonous worlds with the threat of annihilation. While the massive station is evidence of the evil that was the Galactic Empire, it was also proof of the New Order's greatest weakness -- the belief that technology and terror were superior to the will of oppressed beings fighting for freedom. 
The Death Star was a battle station the size of a small moon. It had a formidable array of turbolasers and tractor beam projectors, giving it the firepower of greater than half the Imperial starfleet. Within its cavernous interior were legions of Imperial troops and fightercraft, as well as all manner of detention blocks and interrogation cells. The Death Star was spherical, and dark gray in color. Located on the Death Star's northern hemisphere was a concave disk housing the station's main laser weapon. 
The technical schematics for the Death Star were developed by the cutting edge technologists of the Confederacy of Independent Systems during the Clone Wars. With the defeat of the Separatists and the Republic's transformation into Empire, the Death Star project fell under the command of Grand Moff Tarkin, one the Empire's preeminent governors. The Death Star was developed in secret, through many difficulties over a span of almost 20 years. Rebel Alliance spies were nonetheless able to learn of the weapon's existence, and stole vital technical schematics from guarded Imperial vaults. These desperate spies transmitted this data to Rebel leader Princess Leia Organa, who stored the plans in R2-D2's memory systems. 
In a brutal display of the Death Star's power, Grand Moff Tarkin targeted its prime weapon at the peaceful world of Alderaan. Leia Organa, an Imperial captive at the time, was forced to watch as the searing laser blast split apart her beloved world, turning the planet and its populace into orbital ash and debris. 
Using the stolen technical data, Alliance tacticians were able to pinpoint a crucial flaw in the Death Star's design. A small ray-shielded thermal exhaust port led directly from the surface of the station into the heart of its colossal reactor. If the port could be breached by proton torpedoes, then the resulting chain reaction would destroy the station. 
The Rebel Alliance boldly launched its available starfighter forces against the station. The Imperials were so confident in the Death Star's might that they never considered the Rebel fighters a viable threat. After all, the station was designed to withstand a full frontal assault from large capital ships. At first, the Empire didn't even launch TIE fighters to counter the attack. 
With the aid of Han Solo, the spirit of Obi-Wan Kenobi, and the power of the Force, Luke Skywalker was able to successfully hit the small target, and triggered the Death Star's demise. 
Over three years later, the threat of the Death Star returned, as the Alliance discovered a second, larger Death Star under construction over the remote forest moon of Endor.