What it is
Gigaton is a huge ball of absorbed energy that contuines to absorb planets, stars, powerful beings and so on and so forth. Now a days it has grown bigger than a galaxy.
Who Owns it
The person who owns Gigaton is Ethanus Primeus.
Ethanus after a major defeat with a battle with his sister stumbled apon a strange astroid that absorbed energy. He used that to make Gigaton to use it as a "recharge" station. As time went by he found out it can absorb things other than pure energy. He also found out how to make it into a bomb. Such a powerful bomb that it would when gone off make all evil in the universe disapere with out trace.
Where it Gets its Energy
It collects energy by absorbing items in a strange dimension where there is no form of life.