Peganthrope

Peganthropes are a fanmade race of Neutral Good planar therianthropes for the Planescape setting of Advanced Dungeons & Dragons 2nd edition. Like their counterparts the werestag and werebunny, they debuted on the Mimir.net website, and now survive in the Planescape Creature Codex netbook.

Either solely or mostly male (the lore only focuses on the male ones, but the opening paragraph states that they are only "mostly male"), peganthropes are a therianthrope species native to the plains and open forests of the Upper Planes, having the ability to assume the form of a human, a pegasus, or a hybrid thereof. Sages are unsure if this was meant as a blessing for humans or a curse on pegasi. Some have suggested that they might be the proxies of one or more Good-aligned gods, but nobody really knows anything about where they come from or how they came to be.

In their human forms, peganthropes look like incredibly beautiful people (Charisma 18-20, minimum) with long, flowing locks of hair matching the color of their pegasus-form's mane (usually worn in a ponytail) and big brown eyes. Their pegasus form just looks (and fights) like a regular pegasus. Their hybrid form is basically an anthropomorphic pegasus; a humanoid upper body, a horse's head, fur, legs and tail, and angel-like feathered wings. Though their humanoid and hybrid forms are formidably strong (Strength 17), they prefer to avoid violence... although they usually carry intricately decorated maces to defend themselves with!

Peganthropes are described as loners who basically exploit their beauty to make their lives easier and to hook up with an endless series of one-night stands. No, seriously! This is the entirety of their Habitat/Society entry:

Peganthropes are solitary creatures. They roam the Upper Planar forests, living off the charity of others (but never abusing it). Some of them delight in seducing mortal women and living with them for a couple of years, but in the end they love their freedom more, and leave for the plains again, leaving their wives in despair, lonely and sad. This is about the only moral flaw one has ever found in a peganthrope.

Add in that male peganthropes can cast Charm Person on humanoid women who meet their eyes regardless of which form they're in, and nothing being said of what happens with female peganthropes (assuming they exist), and... yeah, this is up there with the dryad in being kind of sleazy when you stop and think about it.