Darkrai is a black, shadow-like Pokémon. It has a small head with a white fog-like ghostly plume billowing from its head covering one of its bright blue eyes, with the portion on its face resembling hair. It also has a red spiky growth around its neck. It has skinny arms and long black tatters hanging from its shoulders. It also has black, claw-like hands. It has the slight appearance of an hourglass figure and appears to be wearing an old, ripped cloak. It normally does not have any sort of legs, but it is able to extend stilt-like appendages in their place. In self-defense, Darkrai can retract its head and white "plume" into the pit atop its torso fringed by the aforementioned red growth.
Darkrai is known to "inhabit" dreams and causes the target to have unending nightmares, which can be stopped if exposed to a Lunar Feather from Cresselia. However, the "unleashing of nightmares" is actually a defense mechanism, instead of an intentionally malicious act. Darkrai is capable of flying at high speeds, and it can become a shadow in order to escape danger or contact with humans. It is also capable of some human speech. In The Rise of Darkrai, it was shown its power was weaker than that of Dialga and Palkia. Its relationship to its counterpart, Cresselia, can vary between individuals and canons, with some being antagonistic, as seen Sleepless In Pre-Battle! and Pokémon Mystery Dungeon: Explorers of Time, Darkness, and Sky, or cooperative, as seen in Nightfall? Nightmares! and A Midsummer Night's Light!. As seen in Sleepless In Pre-Battle!, Darkrai does not only cause nightmares; it is also attracted to them. It can also go around objects it is attracted to several times, as seen in the mentioned episode and Pokémon Ranger: Shadows of Almia. Darkrai is said to be active on nights of the new moon. Darkrai possibly feeds off dreams, characterized by its association with never-ending nightmares.
Darkrai made its main series debut in Sleepless In Pre-Battle!. Unlike the Darkrai in The Rise of Darkrai, this Darkrai was maliciously causing nightmares, much like the one in the games. According to Officer Jenny, it comes at a certain time every year. In the episode, however, it came earlier due to it being lured out by Team Rocket's machine, which was also causing nightmares. Cresselia is normally in the same place as Darkrai to stop it from giving nightmares, but due to Darkrai's early arrival, the people in Canalave City had nightmares for several days. One night, it was concealing itself when Cresselia used its abilities to reveal it from the darkness. The two then battled and Darkrai hid itself once more in the shadows.
A Pitch-Black Pokémon. It becomes active on nights of the new moon. This legendary Pokémon has the power to lull people to sleep and fill their heads with dreams. Proverbs say that Darkrai will make people have terrifying dreams on moonless nights. A Dark-type Pokémon, Darkrai uses the Dark Voidmove, along with Embargo, which stops foes from using held items.
Darkrai appears as a Poké Ball Pokémon. It puts fighters to sleep and damages them by using Dark Void. It also appears as a trophy in both versions of the game.
NA: This Dark-type Pokémon can cause people and other Pokémon to experience nightmares. While it is floating in the air, it tucks its legs in so far, it looks like they vanish! In battle it will use a move called Dark Void, which sucks in surrounding opponents and puts them into a deep sleep.
PAl: A Pokémon shrouded in mystery, Darkrai has the ability to implant nightmares into the minds of both humans and Pokémon. It has legs, but seems to prefer to float in the air. Its favourite move in this game is Dark Void. When this attack hits something, it creates a vortex that sucks in fighters and puts them to sleep.
Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness: Darkrai is revealed to be the main antagonist of the game in the post-game story. He wants to cover the world in darkness, and was behind the collapse of the Temporal Tower in the main storyline of the game. His interference is also the reason the player was separated from Grovyle and turned into a Pokémon. In the post-game story, he turns his attention to distorting the fabric of space to cover the world in darkness.
Sailor Eldritch's son says "Dar... Dark... Is watching me..." in his sleep before the player cures his nightmare. It is assumed that he is talking about Darkrai, as it is known to give its victims horrific nightmares.
In the early Japanese versions of Diamond and Pearl, Darkrai can be caught with the Surf glitch. However, this glitch was fixed in other language versions. Another glitch has been discovered that allows players of other language releases to reach Darkrai without the Member Card.
This has been remedied in Pokémon Platinum, however, as Darkrai itself will not appear on the island without the event ticket.
Despite being a gender-unknown Pokémon, the Darkrai in Pokémon Mystery Dungeon: Explorers of Time, Explorers of Darkness, and Explorers of Sky is referred to as a male.
Darkrai's appearance and abilities suggest it is based on the concept of nightmares or a mare. Resembling a shadow, it may also have been inspired by the bogeyman, the Greek god Morpheus, genies (or jinn), or the Oneiroi, namely Phobetor. It may also be based on the nocnitsa from Slavic folklore, an evil spirit that torments children with horrible nightmares, slowly draining them of their life energy with each passing night. Supposedly, the only way to protect oneself from a nocnitsa is by placing a knife or special stone underneath a pillow, similar to how victims of Darkrai's nightmares can only be woken up with the Lunar Feather. In contrast to its counterpart Cresselia's association with the crescent moon, Darkrai appears to represent the new moon.
Darkrai may be a combination of dark and 暗い kurai (dark).