Death Star II

The Death Star II was a super-weapon that the Galactic Empire designed, and it was being made to be bigger and more destructive than its model, the Death Star I. Luckily, it never reached full construction. Many Rebellion fighters flew into the Death Star's interior, and destroyed the main reactor (where Palpatine died), and that caused the Death Star II to be destroyed.

However, its successor, Starkiller Base, was far bigger and more destructive than the 2 Death Stars combined, and it could destroy entire star systems.