Nocturnal, diurnal, and times between

Most predators hunt at dusk or at night so any type of werebeast would fall under that. So would ghouls, lichts, demons, i.e. any of the hellbent species. I would think power times being sunset--just after, sunrise--just before, & midnight. Other special times would correspond to equinoxes, solstices, moondark, full moon, eclipses, comets, meteor showers, planetary alignments, anniversaries of dark deeds or gods' acts, etc.

Lots of animals prefer certain times of day to do certain things - so if there are magic animals in your world, then their magic might wax and wane accordingly.

Folklore is full of mundane animals that are thought to have magical properties - it's almost the rule rather than the exception.

The shrew, for instance, was thought in mediaeval times to be terribly venomous. Many shrews are diurnal, but some are solely nocturnal. Some shrews travel in family packs. Many rove the ground; some climb trees. They also must eat around 90% of their own body weight every day, and can't hibernate. Many use echolocation much like a bat. Put these together and you suddenly have an interesting night-monster: a pack of territorial hunting shrews coming down on camping travellers like a horde of venemous mice!

The pelican was thought to strike its own breast to feed its young from its blood. Pelicans are diurnal, but often gather at both dawn and sunset. Perhaps pelican blood is nourishing - even healing - at those hours?

In Brazil, vampire bats are thought to 'own' certain plants, such as tobacco. Be disrespectful of the tobacco-plants, and the vamp bats will get you! They're a nocturnal hunter, of course.

In some Asian traditions, a fungus growing from a toad's head has the secret of immortality. Many Europeans thought that a 'toad stone' - a jewel that can be found growing in a toad's head - would change colour to detect poison. Toads often like to be active around dusk, so there's a potential story-quest idea: find the toad-stone in the marshes in the dusky gloom!

Mediaeval animals are very rich with magic - far richer than most 'High Fantasy' stories suggest. Most animals have very fixed habits, so you're almost spoiled for choice here!

Hope this helps!

Just about all monsters are active only at night. Except for the ones that eat naughty children for playing in forbidden places, they're active all the time.

Now I'm bothered. What kind of monsters are diurnal?

Oh! I betcha there are plenty of desert dwelling diurnal monsters. Like genies. I seem to recall that they and a few others from the Arabian Nights were active in the daytime.

Sarpedon said:

Oh! I betcha there are plenty of desert dwelling diurnal monsters. Like genies. I seem to recall that they and a few others from the Arabian Nights were active in the daytime.

Click to expand...

I don't recall any canonical time restrictions on djinn, but they are supposed to be made of smokeless fire, so they wouldn't mind the heat.

You could take a biological approach to the whole thing, if you wanted. Basilisks? Traditionally, that's a snake. (Okay, some are half chicken, but I've always used "cockatrice" for those.) Snakes are cold-blooded. They sun themselves on rocks to get their body temperature up and make themselves active. So maybe basilisks are diurnal. Gryphons are part hawk; they're probably well-adapted for daytime hunting. Unicorns are often compared to deer, so maybe they're most active at dawn and dusk.

And so forth.

Izunya

You could have some Crepuscular, active at twilight (dawn & dusk ^took too long to post) creatures as well, few predators are active at the time so it would be a good place to put smaller predators or things that couldn't go out when predators are around, and could be thought of as a relatively safe time.
Fairies for instance, otherwise they'd be eaten by birds & owls, still have to worry about cats though.

For more ideas, Google "bestiary" and "medieval."

Also, ghosts are famously time-bound - appearing at the hour of their death, for instance.

In Madagascar, lemurs are considered to be "forest ghosts."

Oh, some haunts are stuck to a time, some to a locale, some to a person or object, or any combo of the above.

Some nasties will come if blood is spilled in a certain place--doesn't need to be on purpose, then there's reading of sacred/profane texts, opening containers, breaking seals, ie: you're screwed 6 ways to sunday :}

It'd be cool if something dire happened everytime somone opened the mayonaisse between 4 and 6 on a December afternoon.

Basically, the sky is the limit.

I also do curses, weddings, and bar mitzvahs :}