In the Spaceman Spiff universe, the titular hero refers more than once to Planet Zog. Whether there are several planets named Zog or just one is unknown, but Zog seems to change every time it is visited.
The first time, Spaceman Spiff saw Zog from space, claiming that its "cratered, scarred surface" had never been seen before by Earthlings. This could imply he was the first human to visit it.
The second time Zog was mentioned, it was a civilized planet, and the comic.
featured an alien metropolis inhabited by green, blob-like, one-eyed aliens. The planet was briefly seen from space, and the craters from its first appearance were not visible. However, a planet was seen in the first panel that was very similar to the original Zog; it is unknown whether this Zog and that on which Spiff lands are one and the same.
In Zog's last appearance, the planet was the home of the hostile zogs. Spiff called it "dismal", in blatant opposition to the prosperous world of the second appearance. This could indicate an aggressive takeover of the planet by the warlike zogs.