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First appearance

Sonic Adventure 2

in other media
Real-world designer(s)

Sonic Team

Biographical overview

50+ (deceased)


Gerald Robotnik


Space Colony ARK

Also known as
  • The Prototype of the Ultimate Life Form
  • Ugly Prototype (by Shadow)
  • Creep (by Sonic and Shadow)

Shadow the Hedgehog (Younger sibling)

Physical description

Genetically Engineered Giant Lizard


N/A (Refered to as male)


17.37 m (57 ft.)


87.5 tons




Not Known, has gun turret-like eyes

Alignment and character traits



Space Colony ARK, Gerald Robotnik, destruction


Shadow, Sonic, Earth

Skills, abilities and powers
  • Chaos Powers
  • Regeneration
  • Inhuman durability
  • Spitting energy balls
  • Laser Beams
  • Asexual reproduction
  • Creating and controlling pink orbs
  • Whipping with its tail
  • Bite
  • Gravity manipulation
  • Finalhazard
Moves and techniques

Chaos Control

The Biolizard (バイオリザード Baiorizādo?) (also known as The Prototype of the Ultimate Life Form) is a creature which appeared in Sonic Adventure 2 as the final boss. It appears as a giant lizard with a life support system on its back with tubes running down its neck to its head. The Biolizard is 85 meters (280 feet) long, 30 meters (100 feet) wide, 19.5 meters (64 feet) at the tallest point on its back, and weighs 87.5 tons.[1] After the final version of the Ultimate Life Form (a.k.a.Shadow) was created, the Biolizard was supposed to be encapsulated, but never was.


Sonic Adventure 2

The Biolizard was an early version of Project Shadow, a government project run by Professor Gerald Robotnik that was intended to create an "Ultimate Life Form" as a first step towards humanity discovering the secret of immortality. This creature is an ultimate immortal, or so the scientists thought. Due to the experiments weakening the Biolizard, it later needed a life support system. While the Biolizard was successful in the way that it could regenerate, restore itself, and self-reproduce, it was also unruly and dangerous.[2] It was closed down when Gerald, with the aid of the alien Black Doom, produced a more advanced being: Shadow the Hedgehog.

When GUN came to Space Colony ARK in order to put a stop to Gerald Robotniks plans, they found the Biolizard and shut it down. It didn't go without a fight, however, and it destroyed almost the entire group of GUN soldiers.

The Biolizard remained in suspended animation aboard the ARK until the present day, when Doctor Eggman placed the seven Chaos Emeralds into the Eclipse Cannon. This initiated a program created by Gerald Robotnik, which used the power of the Chaos Emeralds to send the ARK into a collision course with the Earth. Presumably, Robotnik, prior to his execution, also programmed the Biolizard with attaching itself with the ARK, having anticipated the likelihood that someone might interfere with the Chaos Emeralds. Eggman joined forces with Sonic the Hedgehog and friends to prevent this doomsday scenario, and they tried to pull the ARK into orbit again by using Knuckles' Master Emerald to deactivate the Chaos Emeralds and stopping the ARK. Shortly before Dr. Eggman activated the Eclipse Cannon, Rouge also located a report on the Biolizard on Gerald Robotnik's main computer, to which she later exposed to Shadow the Hedgehog, with the implication that he's not actually the Ultimate Life Form after the latter stumbled upon her plans of stealing the Chaos Emeralds.

However, when Sonic and Knuckles entered the Cannon's Core, the Biolizard awakened, determined to keep the ARK on its path to Earth. Later, Amy Rose convinced Shadow to help save the Earth (Shadow had a flashback about his best friend, Maria Robotnik.) Shadow fought and won against the giant reptile by damaging its life support system. The Biolizard then used Chaos Control to teleport outside of the ARK and fuse with the space colony itself, becoming FinalHazard, the final boss of the game. It was fought by the combined power of Super Sonic and Super Shadow, who then used Chaos Control to place the ARK back into orbit. Both Shadow and the FinalHazard fall to their apparent deaths (though it is later revealed that Shadow survived).

Shadow the Hedgehog

The Biolizard was mentioned in Shadow the Hedgehog, but only in one of Shadow's flashbacks, when he remembers his apparent death after defeating it. The Biolizard was likely just an example of Gerald's work before Black Doom assisted him, and thus is of little interest to the Black Arms and wasn't stable because he didn't have Black Doom's DNA. However, it is noted that after Black Doom transforms into Devil Doom, he has an identical cry to that of Biolizard. Several other Black Arms have similar cries. Also, the Black Annelids, Black Worms, and larval black warriors ("Death Leeches"), have a skin texture very similar to the Biolizard's. This presents the possibility of the Biolizard actually being a Black Arms experiment, but it was simply unsuccessful. As it turns out, Devil Doom and Biolizard's cry is just a reused version of Perfect Chaos' cry.

Sonic Generations

Modern Sonic fights the Biolizard in the Cannon's Core in the Nintendo 3DS version. The boss fight remains somewhat unchanged from his Sonic Adventure 2 appearance except done on a 2D plane. He also seems to have gotten stronger as at times, balls of light can appear in front of Sonic as he runs from the Biolizard's head or tail, which must be jumped or slid under. He also has a new tail slam attack and he chases Sonic as he tries to crush him with his tail.

Appearances in Other Media

Sonic X

The Biolizard in Sonic X.

The Biolizard's role in the anime Sonic X parallels the one it plays in Sonic Adventure 2. It appears in episode 38.

In the series, the creature is not specifically named as a prototype of Project Shadow. In the original Japanese version, Knuckles identified the Biolizard, but in the English dub, it was unnamed, and Knuckles instead simply stated that he wouldn't let the monster get the Master Emerald. When Professor Gerald's diary reveals what really happened on the ARK 50 years ago, a small green lizard was shown that could possibly have been what the Biolizard looked like before being modified to its current state.

Archie Comics

ARK Monster
The Biolizard in Archie's Sonic the Hedgehog
The Biolizard also appeared in the Archie Comics' continuity following the Sonic Adventure 2 comic adaption. However it was not until Sonic Universe #2, which retold the story, that the Biolizard made a physical appearance.

The Biolizard had been guarding the shrine room aboard the Space Colony ARK since 3186 for fifty years until 3236, when Dr. Eggman released Shadow the Hedgehog from stasis and used the ARK in his attempts at world domination. After Shadow betrayed him and fought alongside Sonic the Hedgehog, the Biolizard used Chaos Control and pulled the ARK towards Mobius by fusing itself with the Eclipse Cannon, only to be stopped by the combined efforts of Super Sonic and Super Shadow.


Shadow fighting the Biolizard.

As the prototype of the ultimate life form, which was aimed to have immortality, the Biolizard has the abilities attributed to the desired end-product: regeneration, self-restoration, and self-reproduction. However, the various experiments had severely weakened the specimen, and it required a life-support system to keep it alive, thus its creators deemed it a failed prototype.

The Biolizard's life support system is able to make its skin immune to all outside attacks as long as it is functional, absorbing any attack upon contact; however it also serves as the creature's weakpoint as destroying the system leaves it vulnerable. The Biolizard primarily fights by spitting dark energy balls, biting, or lashing its tail. However the lizard seems to exhaust itself these attacks which leaves it vulnerable to attacks to its life support system; such as grinding up the wires that connect the Biolizard's head to the system on its back to attack it. When its system has become damaged enough, the Biolizard resorts to a new technique where it creates dozens of pink egg-like orbs in the air that can home in on targets; however these eggs have a weakness in that they can be used as stepping stones to reach and attack the life support system again. The creature has one last ditch ability to use when it is on the verge of defeat, it will somehow usurp the gravity in the area to lift up opponents into the air which it then fills with orbs; but it is still possible to navigate through the orbs to attack the life support system.

The Biolizard has the ability to use the power of the Chaos Emeralds to both warp time and space with Chaos Control or enhance itself by transforming into FinalHazard. Its enhanced abilities include the ability to fire large pink energy beams from its broken life support system and create red orbs similar to the pink ones before. The FinalHazard uses the orbs to cover itself as a shield and fires them at opponents. However as its life support system has been demolished, the harsh conditions of space are creating large boils all over the FinalHazard's body, which are its new vulnerable points that are open to attacks.

Theme songs



Biolizard file 2
Lab report reveals that Biolizard was made on January 27th at 12:30 a.m.
  • According to Rouge's report in a cutscene in Sonic Adventure 2, Biolizard was made on 27 January at 12:30 a.m. The report also claimed that its eternal engine and organ for activating Chaos Control were working nominally, although it yielded higher results than expected. The Biolizard was also noted by Professor Gerald Robotnik to have grown to 2.7 meters and 350kg only a couple of days after its "birth," thus resulting in his request for the control of its vital organs to be reinforced. During the time of the report, it was also noted to not be able to walk yet, although its neck and tail were already powerful, possessed sensitivity to temperature changes, and then-currently had a low learning rate, making it closer to an animal, and thus requiring that the Biolizard be under observation.
  • According to Rouge the Bat's report in the official strategy guide from Sega, the pink-orb objects the Biolizard produces are produced through asexual reproduction, which means that there could have been more than one Biolizard, however this is unlikely. It is often assumed that the Biolizard, is in fact, female (due to the eggs), but this is unlikely because, additionally, the Omochao that appears during the battle refers to the Biolizard as a "he". The misconception is due to the fact that it appears to reproduce asexually, however asexual reproduction is largely done by species without clear gender differences and in the case of the Biolizard it's most likely that it's hermaphroditic.
  • His ability to use Chaos Control is resemble to black doom that he can also do it
  • When Biolizard summons the pink spheres and later levitates Shadow, the roar used is the same roar used for Perfect Chaos in Sonic Adventure, but with a different pitch. In the 3DS version of Sonic Generations, Biolizard 's roar is now reused from Dark Gaia Phoenix's from Sonic Unleashed.
  • The Dreamcast version of Sonic Adventure 2 had glitches in the game that led to unavoidable deaths when fighting the Biolizard (such as landing in the water as opposed to on the platform).
  • When playing the Dragon Slayer mission in Sonic and the Black Knight, Sonic sometimes mentions the Biolizard. The Earth Dragon, in fact, may be the Arthurian version of the Biolizard due to being so similar in body type, having the same neck, and even a similar roar.
  • When the Biolizard becomes FinalHazard, it loses some limbs like a missing arm, which might have been caused from its fight with Shadow or when attaching itself to the Eclipse Cannon.
  • In Sonic X and Archie comics, the Biolizard appears to have back legs, while in Sonic Adventure 2, it has two flipper like appendages located in front of its tail.
  • After defeating the Biolizard in Sonic Generations (3DS), the following cutscene shows Sonic saying he fought it before. Technically, he didn't fight the Biolizard in its normal form (it was fought by Shadow) but he did fight it when it transformed into the FinalHazard.


In addition to information taken from the Sonic the Hedgehog games themselves, content from the instruction booklets of the U.S. and Japanese versions of the games were also used as references for this article.

  1. Biolizard size information from Sonic X
  2. Rouge's report on the Ultimate Life Form, translated from Japanese

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