I typically don’t use elemental creatures in any of my games, but that doesn’t mean I’ve never used them. I once wanted to run an adventure in the bowels of an active volcano. The players were tasked by the temple of a nearby town threatened by the volcano’s eruption to find the cause of the volcano’s activity and stop it. In the end it was a giant Magma Elemental that had taken the form of a dragon and was using the Volcano to feed her energy to birth her offspring. However, this was not the Elemental I’m talking about for my “favorite”. No, my favorite elemental is the Magmin and in this particular adventure they served (reluctantly) as the body guards of the “Magma Dragon Queen”.
To me the Magmin’s where funny yet dangerous little creatures like the Grunts of Halo and the players would often find them bickering and arguing and would often fall over at the sight of the party and pretend to be asleep.
After the “Magma Dragon Queen” was defeated the Magmin were (accidently) set lose on the town and the players spent several games getting rid of the pranksters as they came to enjoy pulling slightly dangerous pranks on the locals. When they did leave it was after the players relented and paid the tavern owner for a ten year supply of ale which the Magmin would come back for on a yearly basis.