Alicorns

Alicorns are winged unicorns, but with a deadly appetite: they feed on meat, and they find human meat sweetest of all. They run in wild herds in the foothills of the mountains, where people generally give them a wide berth.
Alicorn horns are priceless, though, as they can be ground into a powder and used in a potion to grant invincibility for a time. This has led to an illegal trade in alicorns, with specially trained hunters braving the herds to slay the creatures and retrieve their horns.
Alicorns are beautiful creatures from a distance, with pearlescent wings reaching a span of six to thirteen feet (depending on the size of the alicorn). The wingtips are usually some bright color, typically red or blue. Their horns are hard and appear a dull grey in the daylight, but after dark they begin to glow. Their eyes are a warm brown, and their skin is light or dark grey with hair in tones of brown, white, and silver. Their manes are usually in a constrasting color to their bodies--so, a white alicorn will likely have a black mane. Their teeth are the most disturbing, though, with deadly sharp fangs hidden in two rows within their muzzles. They do not carry natural venom, but a bite from an alicorn can quickly become infected, leading to an excruciating death if not treated quickly.
Alicorns have a disturbingly intelligent social structure, with a clearly defined leader over each specific herd. The leader is always a male, and he will have a group of five to seven mares with whom he breeds. These family units stay together until the young are a year old, after which they leave to create new herds. This prevents the issues that might arise from excessive inbreeding and also eliminates the need for fighting for dominance within the herds.
Despite their bloodthirsty tendencies, alicorns have never been known to consume one another. They also seem to respect their distant relatives, the unicorns and the pegasi, though they become territorial if even these come too close. All other creatures are fair game, though, and all know to stay well away from their domains.