One creature I like to run frequently (even if the players never discover what it is) is elementals. What I don't do is make elementals a simple "rock monster" or "magic dust devil" or "roving bonfire".
That gets stale, fast.
I run an elemental much in the same way as I would run a ghost or a demon. Primarily it infests and manipulates a region. A water elemental in a pond might absorb the water from the surrounding area and create a desert (or flood the region into a swamp). It has (to varying degrees based on the power of the elemental) the ability to be aware of the happenings in its haunted region based on its element. A fire elemental might be able to see and hear wherever a candle burns, an air elemental could hear where the wind blows. A certain level of control over the element in the region would also be present.
But if you manage to track down the elemental to the creature itself, it won't present itself in the traditional RPG manner, but more often as some kind of creature or form related to the element.
A water elemental might show as a giant fish, an earth elemental might present itself as a stone statue or a mole-man. A fire elemental might show as a salamander, or a red draconian creature, perhaps a man running around on fire screaming and an air elemental might show itself as a giant silver eagle.
Perhaps it is just me, but I prefer the players to not know exactly what they are facing, but to have an idea. It increases the mystery in my view.
The Necronomicon, Family Skiner Edition.
4 hours ago