"Night of the Beast" was originally published in Tales of Terror Picture Library #3 by the UK publisher M.V Features Limited/Famepress:
This was reprinted by Page Publications at least three times - firstly in Tales of Terror Picture Library #2:
Secondly in Tales of Terror Picture Library #4:
And thirdly in Horror Suspense Library #2:
So Keith Chatto produced three different covers for the same story.
The first one is obviously based on the original cover.
The next two appear to be original - that is, not based on the source material, as the images do not resemble any such panels in the story, apart from the green monster.
The cover to Tales of Terror Picture Library #4 has long been a favourite of mine.