10 Supervillains Who Thought They Were The Hero
2. Relic
Former Green Lantern, Kyle Rayner, stumbled upon a giant cyst at the edge of the universe guarded by a space walrus on skis. (That sentence can only exist in comics.) When the cyst burst open, it released a colossal entity called Relic. Relic reveals he is from the previous universe and he must destroy all Lanterns to avoid the current universe's destruction.
You see, Lanterns use their Power Rings to create objects (weapons, shields, tools, etc.) to help them police the cosmos. Relic learned that every time Lanterns uses their Rings, they tap into a universal energy called The Reservoir.
Once the Reservoir is empty, the universe will end. Relic tried to explain this in his universe but he was ignored. To ensure the current universe doesn't suffer the same fate, Relic destroyed the source of the Power Rings' energy, the Green Lantern Central Battery. Since the Battery was connected to the core of the Green Lanterns' homeworld of Oa, the planet imploded.
Luckily, The Reservoir was refuelled by combining the power of all the Lanterns. However, if Relic knew this tactic would work, he never would have waged war against the Lanterns since he takes no joy in killing.