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These ghosts can only be staved off with light.

— Description, Sonic the Hedgehog Encyclo-speed-ia

The Hyudoro[2] (ヒュードロ[3] Hyūdoro?), also known as the Ghost,[1] is a creature that appears in the Sonic the Hedgehog series. It is a breed of ghosts that lurks in Sandopolis Zone and other haunted areas.



The Hyudoros that appeared during the second part of the Angel Island incident look like small, hovering creatures with a roughly spherical, white body with two horns on the head and two angry-looking black eyes each. This appearance, however, varies depending on how lit their surroundings are; the darker the environment they are in is, the larger and more menacing-looking they will appear.

The Hyudoros that appeared during the Ifrit incident look very different from their counterparts in Sandopolis Zone. They are now slightly wider and taller, giving them a more humanoid anatomy. Their bodies are also more transparent and are given a grayish hue. These Hyudoros also have larger, sharper horns on their heads.

Characteristics and culture

Hyudoros usually reside in dark, haunted areas. In terms of behavior, they appear to be very hostile towards outsiders, lurking around their victims and usually attacking them. However, when their surroundings are light enough, they become more passive and simply wonder around outsiders, never attempting to attack them.

Powers and abilities

Being ghosts, Hyudoros are capable of traversing through objects without problem, though it appears that they are unable to pass through certain objects such as Capsules. In addition, Hyudoros are virtually invulnerable. Also, they appear to be very fast, capable of keeping up with Sonic, who can run at hypersonic speeds.[4]

Hyudoros have some weaknesses too; despite their invulnerability, they can be ridden of for a short period of time through a Spin Attack-related move. Also, as they rely on darkness to attack their victims, they get weaker the brighter their surroundings are, ultimately making some vulnerable to attacks and some unable to ambush others.[5]

Game appearances

Sonic the Hedgehog 3 & Knuckles


In Sonic & Knuckles and the lock-on game Sonic the Hedgehog 3 & Knuckles, the player unavoidably encounters a pack of Hyudoros in Act 2 of Sandopolis Zone. It is inferred that the enemies were forced into a capsule by Dr. Robotnik long before Sonic arrived at the zone. Once the player opens the capsule, the Hyudoros will fly out and vanish from sight. As the light in the zone progressively gets darker, however, the Hyudoros will reappear and strafe the character at the top of the screen, where they cannot damage the player nor be defeated.

Hyudoros appear in three different forms, depending on how dark the act currently is. The darker the act becomes, the stronger the Hyudoros will become:

  1. Full Light: In full light, no Hyudoros are visible.
  2. Half Light: In half light, a single Hyudoro appears at the top of the screen. The Hyudoro is small in size and has docile eyes, along with lacking any arms or horns.
  3. Partial Light: In partial light, the Hyudoro will grow slightly bigger, gaining arms and a more menacing expression. A second Hyudoro also becomes visible and joins the first.
  4. Full Darkness: In full darkness, the Hyudoros, now a group of three, will grow even bigger. Horns will appear on their head, and their eyes will furrow into an even angrier expression. In this state, the ghosts also gain the ability to attack the player, relentlessly spawning and charging at the character.

The light switch being pulled on the roof.

In order to keep Hyudoros from attacking, the player can pull on the many light switches scattered around the level; doing so will reset the light level to full light and cause any Hyudoros to despawn for about 15 seconds.

Should the player spin jump into a Hyudoro or touch it while invincible, any attacking Hyudoro will disappear; however, they will quickly reappear at the top of the screen and renew their assault.

Occasionally, if the player is moving fast enough during the attack phase, the Hyudoros may fall off-screen, but they will eventually respawn. Before a Hyudoro starts attacking, they are locked at the top of the screen at all times. Just before a Hyudoro attacks, it will pause briefly before moving slowly in the direction of the player.

As Knuckles the Echidna, the ghosts are already free, since Sonic opened the capsule before Knuckles reached Sandopolis Zone. This is especially dangerous at the beginning of Act 2, since the act starts off completely dark and Knuckles has no Rings.

Once the player reaches the boss area, the Hyudoros will disappear completely and the lights will turn on automatically and permanently.

Sonic Rivals 2

A Hyudoro chasing Sonic and Rouge in Mystic Haunt Zone, from Sonic Rivals 2.

In Sonic Rivals 2, the Hyudoros appear as enemies in Mystic Haunt Zone. In this game, only one Hyudoro appears during one mansion section of the level. The player cannot defeat the Hyudoro, but it is possible to make it disappear by pressing down the switches to light up the interior mansion before the Hyudoro attacks. A giant Hyudoro known as the Egg Phantom also appears as the boss of Mystic Haunt Zone.[5]

In other media

Books and comics

Archie Comics

Main article: Hyudoro (Archie)

In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, the Hyudoros are ghosts that reside in Sandopolis Zone and other areas of Sonic's World.

Sonic the Comic

Sandopolis Ghosts as they appear in Sonic the Comic. Art by Richard Elson.

In the Sonic the Comic series published by Fleetway, the Hyudoros are ghosts inhabiting the Lost Pyramid of Sandopolis. As a part of the pyramid's curse, they will attack any intruders when the light starts to fade. During the comic's run, they attacked Captain Plunder and his crew when they tried to steal the pyramid's treasure and the Chaotix Crew when they paid a visit.


  • As the Sonic Jam strategy guide states, Hyudoros were not created by Dr. Eggman. It also reveals that Eggman infiltrated into the pyramid and trapped the ghosts inside the Capsule, working very hard.[6]
    • Several media mentions that Sandopolis Zone Act 2 takes place in a cursed pyramid, with Dr. Robotnik trying to trap Sonic inside.
  • When the capsule is opened inside of the pyramid, it releases six Hyudoros even though only three of them start to follow the player. It is unknown where the three others have gone, although it is possible that as one of the Hyudoros disappear, another one comes to take place.
  • In Sonic & Knuckles, even though players can avoid opening the capsule containing Hyudoros with Debug Mode or glitching, they will still appear if the player touches any Checkpoint.
  • Hyudoros and Boos are considered to be separate ghost species, but there are a few similarities. Both of them have resided in a dark pyramid and both are able to fly and turn invisible.

Three Hyudoro in LEGO Dimensions.

  • Three Hyudoro make an appearance in the Sandopolis Zone sub-area of the Sonic the Hedgehog World in Lego Dimensions. As in Sonic & Knuckles, they appear after opening a lone capsule. Upon being freed, they split a Gold Brick into three pieces and hide in dark corners of the map. The player must use the Shift Keystone to get near their hiding spots, then push a switch to open the doors they hide behind and defeat them using a character with the Illumination ability.
  • The Hyudoros' name is a Japanese onomatopoeia for the sound a ghost would make.




  1. 1.0 1.1 Sonic the Comic #43 (Sonic & Knuckles Special Part 1)
  2. Flynn, Ian; Sega (8 December 2021). Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. p. 57. ISBN 978-1506719276. "Hyudoro - Accidentally released by Sonic and Tails, it grows bolder and more powerful as the surroundings grow darker."
  3. (in Japanese) ソニックジャム オフィシャルガイド. SoftBank. 2 October 1997. p. 83. ISBN 978-4797303377.
  4. Sonic Adventure (Dreamcast) United States instruction booklet, pg. 18.
  5. 5.0 5.1 Flynn, Ian; Sega (8 December 2021). "Sonic Rivals 2". Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. p. 179. ISBN 978-1506719276. "Egg Phantom - Eggman Nega is hiding inside a massive Hyudoro. Lure it into the light to weaken it enough so you can attack."
  6. "Here's the desert stage, something that hadn't appeared in the series until this point, so we were able to make it relatively free of earlier influences. The ghosts appearing in the second half are the first enemies who weren't made by Eggman. When he infiltrated the pyramid, he must have worked very hard to trap them inside that box." - Takashi Iizuka, Sonic Team Commentary in Sonic Jam Strategy Guide.

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