Most powerful bomb in fiction?

What's the most powerful bomb you can think of in fiction? My vote goes to that South Park NASA nuke that somehow was powerful enough to vaporize tons of fiction characters and the reality itself into white nothingness.

The Blobs Fart Bomb?

The Reality Bomb from the new Doctor Who series. It was supposed to be able to create a chain reaction that would wipe out all realities. Kind of hard to do better than destroying all that is.

cyber-bombs and the Z-Bomb from doctor who were capable of destroying entire planets

the Oblivion Continuum from doctor who could destroy planet and "cause worlds to bleed into other dimensions"

temporal fusion bombs from doctorwho/Torchwood were capable of destroying star systems
 
if the reality bomb is to be considered an actual bomb...then nothing tops it. The reality bomb was capable of cancelling the electrical field that held atoms together and it was capable of destroying the entire universe and all of creation..and capable of reaching all alternate universes making it a multiversal destruction bomb

COIE Anti Monitor.

Yo-momma-geddon.

Null Bomb from marvel which could destroy a whole galaxy.

Kang's bomb which could destroy/doom the universe. Are also worthy of mentioning. They outclass Mageddon.