In episode 24 of season 6 of Adventure Time, Ice King is seen waking up from a dream where a certain reptilian Gunther turns into another, seemingly much older Ice King. The whole dream looks like it's some previous epoch with primal elements of fire, candy, green goo and ice. The reptilian Gunther puts on the magical crown that grants him a wish which makes him very much like the Ice King.
Then we see our "present time" Ice King who, waking up from his dream, makes explosion noises, suggesting that the dream ended with the comet hitting the planet. He then wakes up and is surprised by the scared look of a bunch of penguins in his bedroom. And then we see a comet which could be that comet.
In previous episodes, Death says that the Ice King will only die when the Sun explodes, suggesting that he is practically immortal because of the power given him by his crown. So he could have survived anything, even that.
And in the next episode we find out that a comet appears every 1000 years on the course to hit Earth. Earth has a very serious chunk of it missing, which could suggest that one or multiple of those comets already hit it in the past. Or maybe it could have been only the result of the Mushroom War and all previous comets were successfully avoided.
Is the Ice King we see in the show the original or is he the reptilian Gunther who survived the comet in the past?