Executor-Class Super Saxton Star Dreadbringer

The Executor-Class Super Saxton Star Dreadbringer was 186,000 miles long and the Empire built 600 million of them. To staff their fleet, the Empire had to clone every citizen of the Galaxy a hundred times. This left them no enemies to use the Star Dreadbringers against, at which point everyone turned to the guy next to them and admitted that this had actually been a pretty bad idea.

Their ultimate fate remains a mystery.

Behind the scenes
There has been significant debate about the actual size of Executor-Class Super Saxton Star Dreadbringers. Some fans (known as "idiots" by any respectable Star Wars fan) consider the canonically accepted figures of 600 million 186,000-mile-long vessels to be "unrealistic," even though '''it's canon so shutup DAMMIT!!! THEY'RE BIGGER THAN THE GALAXY!!! WHY CAN'T YOU JUST ACCEPT IT, FOR THE LOVE OF CHRIST?!?!'''