The Sirens are half-woman, half-fish and very fat. They are found in Everlight Reef.
They have ears just like those of the Elves, since presumably, they are 'Elfish' creatures of light magic, their hair is piled very high, and they wear many shells. Like the fairies, their breasts are very obviously large (because they're fat) and are only just covered by a few convenient starfishes. Their tails are curiously covered in spines, which along with their roundness gives them a pointed resemblance to pufferfish.
Sirens can be found both on land and in the water, where they will cling to your Ship if you come too close to them. Their most common attack is to spray water at their enemies, which causes a moderate amount of damage. Their other tactic is to drag a minion underwater with them, drowning it within a few seconds. Since the Overlord cannot be killed this way, the best tactic is to just attack the siren yourself.