The oldest and most wretched of the fair folk are the hags.
Female fairies mature into hags if they survive past a certain age, usually 100 years. Because of the long lives they have to lead to become hags, most fairies have multiple class levels when they reach this age.
Goblins, pixies, dryads and grigs age to become witches of the woods called green hags. The green hag is wise and cruel, and possesses much knowledge of things that should not be known. They live in deep forests and on secluded hilltops, scheming against the civilized folk and contemplating vile magic.
Nymphs and nixies are fey of unearthly beauty closely linked to the water, often a specific lake or pond. They are incredibly vain creatures, and as they age and their beauty begins to fade, many of them lose their minds to despair and shame. Embarrassed by their appearance, they flee to the water and hide from prying eyes. As they grow old beneath the surface, fish gnaw at their bodies and water seeps into their skin. They transform into hideous crones, so awful to behold that those who do see them become physically ill. These are the least powerful of the hags. They waste their youth playing, dancing and fornicating, and seclude themselves in despair when they become older instead of searching for power.
The few ogre and troll women who live to old age become annis’. The annis is a sadistic predator, taking even greater enjoyment in the suffering of others than their younger counterparts. While the fair folk can digest almost anything and survive on very little food, the annis like to gorge themselves on raw meat and prefer eating the flesh of intelligent beings. Despite their eating habits, annis invariably look thin and famished, and get thinner with age. Exceptionally old annis often resemble undead humanoids.
The oldest and most powerful of the fair folk sometimes enter into dangerous pacts with evil spirits and become night hags. Feared even by other fairies, these creatures live to corrupt the souls of both the living and the dead. They enjoy the emotions inspired by bad dreams, and delight in causing them by riding on the backs of sleeping men. The night hags are the only ones of the fair folk who are not actually mortal, and they never die of old age. Most night hags move on to other worlds when they tire of the prime, others are destroyed by the same forces that gave them their power.
Male fairies almost never survive this long, but the rare few who do undergo similar transformations. For example, while practically all ogres are killed by accidents, humans or other ogres, some possess the wits to stay alive and rise to become ogre mages.