Shadow Creature

Crawling Horror=

Terrorbeak=

"Ahhh. Refreshing."

- Maxwell

Shadow Creatures are hostile mobs that begin to attack the player upon reaching 30 sanity points or lower. They will spawn once the player's sanity levels are below 82.5% and they will gradually become more visible as the player's sanity level drops further. They are visible only to the player and cannot be examined.

When the player is insane, up to three of these creatures will spawn around the player and attack. Upon being killed, they will drop Nightmare Fuel, used for crafting several Magic items.

The sanity meter will drop by being near aggressive Shadow Creatures because of their insanity aura, but it will rise by at least 15 points after killing one.

Shadow Creatures also appear in Ruins, spawning from Nightmare Lights and Nightmare Fissures during Nightmare Phase in the Nightmare Cycle. They'll be tangible and hostile to the player regardless of sanity and will pursue the player until the cycle is at the calm stage again. When a Shadow Creature is spawned from a Nightmare Light, killing it will not increase your sanity.

Crawling Horror
Originally believed to be the name of all the Shadow Creatures, the Crawling Horror is now known to be just one type.

It is a large tick-like creature, with many legs, and is the most common of the Shadow Creatures.

While not aggressive (above 15% Sanity), Crawling Horrors will wander around, move away from the player when the player gets too close, and occasionally teleport around the player's vicinity. They can disturb the webbing around Spider Dens, causing inhabiting Spiders to emerge and investigate the cause. They also can prevent items and the ground underneath them from being clicked on, even when they're not entirely solid.

Crawling Horrors turn aggressive when the player's sanity is 15% or below (18 for Willow, 15 to 45 for WX-78, 37.5 for Wickerbottom, 22.5 for Wes and 30 for all other characters). Walking near these will decrease Sanity, and they will restore 15 Sanity and drop Nightmare Fuel when killed.

A version of the Crawling Horror called Crawling Nightmares can be encountered in the Ruins. This version is able to attack even when the player is sane, but they will only spawn from Nightmare Lights when they are completely open. When killed, it will not restore sanity.

Terrorbeak
The Terrorbeak is a creature with an enormous beak and slim body, with several small legs. Like the Crawling Horror, it will attack the player, but is less common. Players can attack them most easily by trapping them on the coast or by hitting them with a Boomerang.

Killing a Terrorbeak with characters with normal sanity (200) while being attacked by Shadow Creatures is a good way of stopping the attacks, as they give 30 Sanity when killed, causing Shadow Creatures to go neutral again, even at 0 sanity.

A version of the Terrorbeak called Nightmarebeaks can be encountered in the Ruins. This version is able to attack even when the player is sane, but they will only spawn from Nightmare Lights when they are completely open. When killed, it will not restore sanity.

Below is the number of hits it takes with each weapon to kill Shadow Creatures when playing with characters with a default damage modifier. The Weather Pain is not included due to the random nature of its projectile.

Mr. Skits
Mr. Skits is a small, serpent-like creature that will watch the player from afar. He also appears above Obelisks when they are raised or lowered. If the player attempts to reach Mr. Skits, he will turn and slither away, disappearing from the screen, and may reappear elsewhere later.

Mr. Skits may also flicker on the screen for a fraction of a second, then disappear.

He will only appear if the sanity level of the player is below 82.5%. He cannot attack, nor can he be attacked. His only purpose is to scare players of Don't Starve.

Shadow Watcher
The Shadow Watcher is a long, thin Shadow Creature which appears around light sources at night (which includes a charged Lightning Rod) from many angles, so it might be upside down. The Shadow Watcher will appear when the player's sanity drops below 65%. It is harmless, and it cannot be attacked. It will usually disappear when player stands on its eyes. When it appears on snow or occasionally on a light background, it will appear as just an outline. This Shadow Creature disappears after dawn breaks.

Besides just frightening the player at night, the purpose of a Shadow Watcher is unknown. However, there is a Shadow Watcher in the source code of the fourth and the sixth William Carter puzzle and one in the fourth puzzle's scene, possibly a hint to a connection between the two entities.

Night Hand
Night Hands are Shadow Creatures that extend from the darkness at night. While not directly attacking the player, Night Hands will attempt to put out fires. Up to 3 Night Hands can spawn at the same time. Their appearance is also marked by a music box playing, which layers as more Hands appear on-screen.

When stepped on, Night Hands will shrink away from the player (with a small insanity aura at -40/min). Once far enough into the darkness, a Night Hand will disappear and the music box will stop playing, though usually the player has to briefly be in total darkness to chase it away. If the player stokes their fire after the Night Hand appears, it is possible to see the "end" of the night hand. Forcing the Night Hand to shrink away until its wrist is touching its "end" will kill the Night Hand.

If not taken care of, a Night Hand (or more) can easily take out a small fire, reducing 50% of the fire's strength each. Night Hands do have the potential to actually put out a fire if this occurs; however, it is somewhat rare, and the more hands that appear, the less they can damage a fire (1 Hand = <60% per hand. 3 Hands = <30% per hand).

If the fire is at its highest strength, then it is unlikely that even three hands can completely snuff it out, so a potential tactic is to max the fire and stand near to max it out again after the attack, although this burns quite a few resources and does not get rid of the Night Hands. A second fire nearby "cancels" Night Hands altogether for the night. A Miner Hat does the same, as does placing fireflies around your base.

Occasionally, even when sanity is over half full, this particular Shadow Creature can still appear.

Eyes
When the player's sanity is below 80%, several Eyes will pop out of the darkness. They are purely for atmosphere and have no effect. They disappear when the player goes to them or the area they are in is lit.

The lower the player's sanity, the more eyes spawn with increased intensity. They will go from round, small, and sometimes curved eyes to larger, sharp, menacing ones. Sometimes trees or other obstacles can block eyes, commonly forming a one-eyed Shadow Creature.

In Epilogue: Checkmate of Adventure Mode, eyes will be visible in the darkness regardless of the player's sanity.

Trivia

 * Shadow Creatures are interpreted to be the mysterious beings Maxwell refers to as "Them", and evidently control the realm the game takes place in.
 * Crawling Horrors and Terrorbeaks will go straight through walls while not aggressive, but if sanity is 30 or lower, they will manifest into a physical form and won't be able to pass through them, provided the walls have been upgraded at least once (they can still pass through/over level 1 walls).
 * It is possible for a lightning strike to extinguish the Night Hand just as it spawns.
 * Their behavior has references to the monsters in Lovecraftian literature, as beings that are so otherworldly they cause humans to go insane, and their ability to move through dimensions. Their names are also allusions to Lovecraftian stories such as The Lurking Fear and The Crawling Chaos.
 * When one is experiencing a sleep paralysis, it's common to see deformed shadowy creatures creeping around the room. This description fits perfectly to the Don't Starve Shadow Creatures. Also note that sleep paralysis is commonly associated with lucid dreaming and in the science menu, description for the Dark Sword is "lucid dreaming damage".
 * The Shadow Creatures spawned in ruins have different names when the Force-Attack button is held: Nightmarebeaks and Crawling Nightmares, possibly referencing how the overuse of nightmare fuel led to the civilization's downfall.
 * Shadow Creatures are immune to Tooth Traps and Bee Mines.
 * Shadow Creatures are the only mobs able to cross the barrier between the Ocean and World at any given time, yet aggressive ones will still try to path find their way around to the player if the player is on the other side of the Ocean from them.
 * When Maxwell uses his Codex Umbra, a group of Mr.Skits will briefly appear when the puppet spawns.
 * Mr. Skits was shown as the "author" for the Lost Fragment mod that was part of the William Carter Puzzles.
 * In the Rain of Giants DLC, during a full moon, if one follows the body of a Shadow Watcher away from a fire, one can see that it ends abruptly.

Bugs

 * Sometimes, a Shadow Watcher will not disappear when day breaks, but instead a few seconds after.
 * Occasionally, after defeating a Night Hand, the music won't stop playing. This appears to stop after saving, quitting, and reloading the game.
 * When the player stands on a Night Hand, it will sometimes play the retreating animation, but it will still continue to extinguish the fire.
 * A Terrorbeak can sometimes have its body disappear, but the beak and legs are still visible (see bottom picture)
 * Sometimes, eyes can glitch so there is only one eye in the "face". When this occurs, all the eyes will be affected.