Quote:is there any Being he ever encountered comparable to Galactus?
In terms of what he does, the closest we got was Omega, in The Three Doctors. The renegade Time Lord was able to utilise a black hole to drain Gallifrey of it's energy which, if unchecked would have led to the death of everyone on the planet.
In terms of sheer power, there are a couple of potential candidates.
Azal (The Daemons), Kronos and other Chronovores (The Time Monster), Sutekh (Pyramids of Mars), The Black Guardian (Seasons 16 and 21), The Eternals (Enlightenment), The Gods of Ragnarok (The Greatest Show in the Galaxy), The Beast (The Impossible Planet) and Akhaten (The Rings of Akhaten) are all ancient, immensely powerful beings, the full extent of which we probably haven't yet seen.
what about the creature that claimed to be satan in the Pit?