Mononoke (Beings)

From Wikipedia:


 * Yōkai (妖怪, "strange apparition") are a class of supernatural entities and spirits in Japanese folklore. The word  'yōkai' is composed of the kanji for "attractive; calamity" and "apparition; mystery; suspicious." Yōkai are also referred to as ayakashi (あやかし), mononoke (物の怪) or mamono (魔物). Yokai are not literally demons in the Western sense of the word, but are instead spirits and entities, whose behaviour can range from malevolent or mischievous to friendly, fortuitous, or helpful to humans.


 * Yōkai often have animal features (such as the kappa, depicted as appearing similar to a turtle, and the tengu, commonly depicted with wings), but may also appear humanoid in appearance, such as the kuchisake-onna. Some yōkai resemble inanimate objects (such as the tsukumogami), while others have no discernible shape. Yōkai are typically described as having spiritual or supernatural abilities, with shapeshifting being the most common trait associated with them. Yōkai that shapeshift are known as bakemono (化け物) or obake (お化け).


 * Japanese folklorists and historians explain yōkai as personifications of "supernatural or unaccountable phenomena to their informants." In the Edo period, many artists, such as Toriyama Sekien, invented new yōkai by taking inspiration from folk tales or purely from their own imagination. Today, several such yōkai (such as the amikiri) are mistaken to originate in more traditional folklore.

In the context of the series:

List of Mononoke:
This is a list of Mononoke seen in the series, Mononoke.

Zashiki-Warashi
Zashiki-warashi (座敷童子, or 座敷童, "parlor child"), sometimes also called Zashiki Bokko (座敷ぼっこ, "parlor boyo"), are spirit-like beings told about mostly in the Iwate Prefecture. They are said to be yokai that live in parlors or storage rooms, and that perform pranks, and that people who see one would be visited with good fortune. There are also legends of how they would bring fortune to families. They are also known from Kunio Yanagita's Tōno Monogatari, Ishigami Mondō, and stories about them appear in the 17th and 18th chapters of the Tōno Monogatari and the 87th chapter titled "Zashiki-warashi" of the Tōno Monogatari Shūi. In the 17th chapter, it is written "families with whom this spirit dwells become prosperous" (kono kami no yadoritamafu ihe ha fūki jizai nari to ifu koto nari). In recent years, television programs and magazines have reported about various Iwate Prefecture ryokan where it is said to be possible to see a zashiki-warashi, such as the Ryokufūsō, the Sugawara Bekkan, and the Warabe.

Umibōzu
The Umibōzu (海坊主, "sea priest") is a paranormal phenomenon or yōkai from Japanese folklore. Other names include Umihōshi (海法師, "sea priest") or Uminyūdō (海入道, "sea priest"). Umibōzu (海坊主, "sea priest") is a paranormal phenomenon or yōkai from Japanese folklore. Other names include Umihōshi (海法師, "sea priest") or Uminyūdō (海入道, "sea priest").

Noppera-bō
The Noppera-bō (のっぺらぼう), or faceless ghost, looks like a human but has no face.

Nue
The Nue (鵺, 鵼, 恠鳥, or 奴延鳥) is described as having the head of a monkey, the legs of a tiger, the body of a dog and the front half of a snake for a tail.