Chaar

Bot World
When Unicron attacked Cybertron in 2005, Optimus Prime was able to defeat the Chaos God using the Matrix, cementing the Autobots' feeling of invulnerability. Without a leader, Cyclonus and the Sweeps settled on Chaar, where they eke out a meager existence while plotting their revenge on the Destroyer of Unicron.

Decepticon World
When Unicron attacked Cybertron in 2005, Megatron forced Autobot prisoner Hot Rod, to open the Matrix that Megatron had ripped out of Optimus Prime's chest. Once Unicron was destroyed, Megatron killed this "Last Autobot," believing then that he had extinguished the final spark of the Autobots forever.