I’ve collected two monsters that are from different ends of the, “I want to meet this in the dead of night” spectrum.
First up, we’ve got the Bunyip:
Honestly, I know very little about Bunyips. They’re aquatic and terrestrial beasts that Australian parents can use to torture children into behaving. The creepiest thing about this monster is that almost unanimously, sources agree that it can handle any terrain, meaning that even the most resourceful kids are doomed if they do something bad. So kids, just…be good.
The next monster is the best and cutest and best. 
It’s a BAKU! They’re adorable and really helpful. These guys eat bad dreams! Leaving the sleeper with only the cushiest of images to whisk them off to sleep. Based almost entirely off of Malaysian tapirs, Baku’s have also been described with tiger and elephant features. For any Pokemon fanatics out there, you might recognize the Baku in one of the original 151:
Yup, reliable ol’ Drowzee here. And his whole Dream Eater schtick has a direct link to the mythology too. I’m not saying that the Japanese have been developing Pokemon since ancient times, but actually that’s what I’m going to stick with.