Take your standard earth elementals and give them the ability to change shape and a sense of humor.
One gang likes to loiter near the entrances to adventuring destinations such as caves, towers, and abandoned temples. If they hear anyone approaching, they assume the form of petrified adventurers. To them, it’s fun to see parties suddenly break open their packs, cursing themselves for forgetting to buy or back a mirror, and proceed forward trying not to look at anything ahead of them. Sometimes they follow the adventurers into the dungeon and repeat the trick, just to see what sort of paranoia they can get out of them.
Recently they changed into the shape of the party that was approaching them, leading to all sorts of discussion about time travel and “shouldn’t we try to unpetrify them in case it’s us?” and “They are evil versions of us and we’ll have to fight them if you do it…”
Maybe if they are impressed with a party, or if the party somehow figures out they’ve been duped, they’ll give them a ring of air elemental control or something for being good sports.
Another elemental has stood as a statue in the capital of the Thracian empire for thirty years. Having destroyed and taken the place of a statue of Emperor Commodus Maximus, he has stood as the centerpiece to an outdoor temple in the great square. He likes to wink and blow kisses to passersby and will grow or shrink the size of his codpiece from day to day.
As the Maximus family has long taken pride in its virility and is sensitive to rumors of inadequacy, this has driven the current Emperor, Claudius Julius Maximus, to exasperation. The elemental is too heavy to move, for one thing, and cannot be damaged by normal stoneworking tools. The elemental’s next trick will be to grow a stone sword out of his back, a hint that Emperor Commodus did NOT die of malaria. Whether this is true is up to the DM…