Harpies are a female bird monster who are known in Greek and Roman mythology to be "snatchers" as their name means "snatchers". In tradition mythology, harpies are supposed to be hybrids of humans (women) and birds. Hesiod calls them two "lovely-haired" creatures, the daughters of Thaumas and Electra (not to be confused with Electra, daughter of King Agamemnon), who were sisters of Iris. Pottery art depicting the harpies featured beautiful women with wings. Roman and Byzantine writers detailed their ugliness.
Also, despite this, harpies aren't combinations of human women and birds in Monster High, but instead, fullbred female monster birds, they are still bird-related monsters who can only be female, through-and-through. Good examples of harpies are Quill Talyntino and Avea Trotter, who is part harpy, part centaur. Harpies are traditionally birds.
In Monster High, a harpy is traditionally a bird-based monster of female sex exclusively. While Quill Talyntino (named after the actor Quentin Tarantino), was typically shown as a backgrounder character in the original first Monster High generation; she typically has a feathery appearance with lacking a beak or bill mouth, and instead having peach-colored lips and a pointed nose. Quill (renamed or referenced to as Harper) is typically a feather-bodied female bird monster with short, feathered "hair", which exposes what appears to be a lack of ears, but like traditional real birds, may just be small holes underneath the sides of her head under her feathers. Quill is named for Quentin Tarantino, and she sports no wings for arms but has a humanoid set of arms and hands with a pair of bird wings in her back.
Quill has anthropomorphic legs and feet, anthropomorphic/humanoid arms and hands with fingers, wears a short-sleeved purple dress, has a pointed, beak-like nose and a set of turquoise feathers for "hair." In Decomposition Class, she is portrayed as Harper, a shy and lonely-demeanor bird monster who has an obsession of shiny things such as coins; a clear reference to how birds in real life like shiny things. She was in a set for a contest by Mattel to be created into a doll as a vote, which she has lost to Finnegan Wake in the polls while also with Gory Fangtell, a vampire girl. Due to this, the person Quill has not fully been made into a character as a doll with a profile, but Mattel may change their minds in the future.
The next harpy in Monster High is Avea Trotter, a unique harpy as being half-centaur, from her father's side (Which actually makes sense since Harpy is a feminine word and traditionally means a woman with a bird's body and wings). Avea Trotter has no interest in traditional bird foods, such as bird seed, peanut butter, or worms; but appreciates traditional common horse foods such as apples, oats, alfalfa, and sugar cubes. Avea is described as a stubborn and opinionated girl. She appears as a natural leader, and in Freaky Fusion, she and Bonita Femur both agree with each other to Neighthan Rot that regular, non-fused monsters do not like hybrids.