Caterkiller

Caterkiller, also spelled Catakiller and known as "Nal" (ナール Nāru) in Japan, is caterpillar-type badnik created by Dr. Robotnik, which makes first appearance in the original Sonic the Hedgehog.

Catakiller seems to be a favorite design of Eggman, since it is re-used in many other forms. For example, a modification of it, called Sandworm, appeared in Sonic & Knuckles in the first act of the Sandopolis Zone.

Sonic the Hedgehog (1991)
Catakiller appears at Marble Zone and Scrap Brain Zone in the 16-bit version of Sonic the Hedgehog. To defeat Caterkiller, the player must jump or roll into/onto its head with the Spin Attack, otherwise the player will take damage, and will scatter the Caterkiller's segments all over the place. If you destroy a Caterkiller in this way, an animal friend will not be freed.

In the 8-bit version of the game with same name Catakillers only appear at Scrap Brain Zone. Caterkillers also have an identical pattern to the 16-bit counterpart, however even if the player manages to destroy these badniks, it doesn't have animal friend inside of it, which is tradition in Master System and Game Gear titles.

Sonic 3D
An unnamed caterpillar badnik with the same appearance is seen in Sonic 3D as it can be found at game's intro cutscene and Green Grove Zone Act 2, leaping between holes in the ground. As seeing spending its time underground, it will pop up from two dark pits which badnik jumps between. Attempting to defeat the badnik with a spin jump while it's in the air may prove difficult, mis-time the leap and Sonic may end up losing his rings (and Flickies) by connecting with the spiked tail. A more cunning method is to charge up a spin dash right on top of the hole; the robot will dive right into the spinning hedgehog and be destroyed, freeing one of Flickies of the Island.

Sonic Jump
The original Catakiller doesn't make appearance until at Mountain Zone in the 2012 remake of Sonic Jump. Caterkillers act like they did in their first appearance, although they like to fall down to the lower platforms.

Sonic Lost World
Caterkiller will make appearance in both Nintendo 3DS and Wii U versions of upcoming Sonic Lost World, as these badniks being found at Windy Hill. During the game, it turns out that badniks, Caterkillers included, got hijacked by Deadly Six. These badniks move on slowly to certain pattern like Snail Blasters and due having segments, the player have to hit the head section with the Homing Attack, because hitting it to the other segment will make both get hit, as Caterkiller will got destroyed while the player loses shield, rings or even life in Nintendo 3DS version.

Defeating Caterkiller is slightly different in both versions. In Wii U version, they are large and the player has to hit on to it's head by doing Homing Attack or stomping. In Nintendo 3DS version, if the player pays attention to the by doing Somersault to the badnik, it will make easier to destroy Caterkiller without getting hit at the same time.

In the end of first act of Windy Hill for Nintendo 3DS, Sonic will also find himself running away of much larger Caterkiller on the linear road with rock obstacles. In this appearance, Caterkiller do have more pink skin instead of purple and does have eyelashes on her eyes, stating the badnik being female. After getting away of Caterkiller, the player reaches to the capsule and completes the first act.

Physical Appearance
The Caterkiller's model is based on a real-life caterpillar, both in its shape and the way it moves across the ground, stretching its four segmented body parts up and down to crawl along its programmed territory. It has two antennae located at the tip of its head.

An interesting feature of this Badnik is its ability to separate its four body parts if one of its 3 spiked segments are hit. As long as the head remains intact, this Badnik will continue to survive, albeit scattered throughout the area. Teeth can be seen on the front of the Caterkiller, but they have never been documented to have attacked with these. Standard colors for the Caterkiller model were a purple body shell with a gray underside, with a smattering of yellow for the antennae and spikes.

Abilities
The Caterkiller's main attack pattern lies in its ability to only have one segment that can be destroyed without any injury to the attacker, making it more of a defensive Badnik than an offensive one. As stated in the Physical Appearance section above, not only will the attacker be hurt if they try to hurt the last three segments, but the segments will detach and scurry around the area, causing even more potential damage. Sonic had to be extremely careful when dispatching these enemies. The Caterkiller will also sometimes turn, but it is possible to hit without taking damage/losing a shield when Sonic is not invincible.

Sonic the Hedgehog Story Comic
Caterkiller appears in Sonic the Hedgehog Story Comic manga. At the beginning of the Sonic the Hedgehog Story Comic Volume 2 story ''Clash!! South Island'', Caterkiller chases Pocky at Marble Zone until Sonic destroys it with his Spin Attack and saves Pocky. A little later Picky emerges from the wreckage of the Caterkiller, serving as an organic battery of the Badnik.

Sonic the Comic
Caterkiller badniks appeared numerous times in early issues of Fleetway's Sonic the Comic as part of Doctor Robotnik's badnik army. Because of a different artist in each story, Caterkiller's appearance has been slightly different. Despite having a strong bite, Caterkillers weren't smart in its early appearances, but at the time, later models have got faster and were able to burrow through the ground. Caterkiller has also been seen in many pin-ups and few covers. It first appeared in issue 1' story "Enter: Sonic", as getting destroyed by Sonic.

In issue 3's story "Mayhem in the Marble Zone", Caterkiller along with others have lead Tufftee's friends to a pit in Marble Zone, who would later threaten to drop Tufftee to the lava pool instead of crushing him. Because of Tufftee's strong nature, the badniks instead send in Badnik Processing Badnik to deal with him until Sonic spins into the action and destroys all badniks and saving Tufftee and his friends.

In issue 12' story "Hidden Danger!", a damaged Caterkiller can be seen terrified as it thinks Sonic evading capture. It was later seen with other badniks, attacking to to Sonic who has memory loss during the story but as his memory comes back, the badniks were quickly destroyed. In issue 111's "Hero of the Beach", Caterkillers were sent tunnelling under the sea to attack Skegpool from below, but during the attack, Tails happens to take them all down at once.

Archie Comics
Caterkiller badniks have also been appear in early issues of the Sonic the Hedgehog series from Archie Comics, appearing as a part of Robotnik's badniks. Sonic first faces a Caterkiller which attempts to block Sonic's path but got hit by a wave of Mega-muck. Some of his operations include being part of a crowd of badniks in Casino Night Zone, trying to ambush a so-called wedding between Sonic and Princess Sally, being once again the first badnik to fight Sonic at the Robo Hobo Jungle, which Sonic points out during the fight and after that, he manages to get information about Nack the Weasel and also threats to drag his head against the ground at high speed. However he let him go.

In issue 119, a second, drastically different looking model of Caterkiller was sent by Eggman to overrun Furville, but Sonic the Hedgehog and Miles "Tails" Prower managed to put it to a stop.

As Sonic decided to visit the Island of Misfit Badniks, Caterkiller and numerous other badniks nabbed him. As usual Sonic quickly beat all badniks, but as Pseudo Sonic arrives, the duel between them makes the island sink down. Caterkiller as leader, seeing Sonic going away, makes a promise that they will return. Badniks with Caterkiller return with revenge plan with enlarging Pseudo Sonic, but got interrupted by the Forty Fathom Freedom Fighters. Caterkiller led the last wave of badniks which includes Jaws, Bat Brain and Buzz Bomber. However as wrapping himself around Ray, it gets knocked out by Pseudo Sonic and all of them got crushed by Big Fluke into a cube.

In issue 226 of Genesis arc., Caterkiller tries to attack Sally in Marble Zone, but got captured and destroyed by Rotor. Other Caterkillers later got destroyed by Sonic and Buzz Bomber. At another place and another time in issue 242, two Caterkillers attack to Sonic, Shadow and Tails in olympic stadium. These models look a little bit different and bigger looking, as these models have no feelers, but they have white blank eyes and a cannon, which sucked Tails and Shadow in. Sonic manages to destroy one, but another one manages to get away and off-screen Eggman captured them to the capsule.

Merchandise
The toy company TOMY has released Caterkiller action figurine during the release of Sonic & Knuckles as it also includes a series of 21 Sonic figurines and these figurines came in packs of four under the Sonic & Knuckles label and were also released individually under a Sonic the Hedgehog label.

Related Badniks and Upgrades
Although Caterkiller haven't make many appearances in games, there exist different modifications that may have based on the Caterkiller.
 * Crawlton from Sonic the Hedgehog 2 is similar in design, almost an 'upgrade' of Caterkiller. It appears in the Mystic Cave Zone, like Sandworm after it, it is blue and yellow rather than purple and yellow.
 * Kemusi is an enemy that is named similar to Caterkiller in Sonic the Hedgehog CD.
 * Dangerous Ball Tower, boss of Gigalopolis Zone from Sonic Chaos seems to be like giant version of Caterkiller.
 * Catakiller Jr. (known as Meramora in Japan), appears in Sonic the Hedgehog 3 as it is the precursor of Caterkiller and has the added ability to hover and protects its body with an energy wave.
 * Sandworm from Sonic & Knuckles greatly resembles the original Caterkiller, although it is blue instead of purple. It does not crawl, instead burrowing through quicksand, and can even leap out of the sand to attack the player. In Japan, both Caterkiller and Sandworm are known as Nal making them the same Badnik.
 * Wood Butarundorf, a boss mecha in Sonic Triple Trouble seems to be another giant modification of Caterkiller.
 * Unnamed Badnik is an analogue to Caterkiller at Botanic Base in Knuckles Chaotix.
 * Boa-Boa in Sonic Adventure seems to be successor of Catakiller Jr..
 * Wamu from Sonic Advance is similar to Catakiller and mostly Catakiller Jr..
 * Kubinaga from Sonic Advance 2 appears to be mix of Caterkiller and Crawlton.
 * Guruguru from Sonic Advance 3 is another successor of Catakiller Jr..
 * Muugaden from Sonic Advance 3 bears resemble to the Catakiller.

Trivia

 * Caterkiller was originally intended to appear in the Spring Yard Zone instead of the Marble Zone, but was switched with Spikes late in development. Caterkiller appears as a default badnik of the Spring Yard Zone in Sonic 1's debug mode.
 * Caterkiller was the first Badnik Sonic encountered in the Archie Comics instead of Moto Bug.
 * Crawlton, a badnik of Sonic the Hedgehog 2 appears in Sonic the Hedgehog: The Movie, but the badnik has a pink color-scheme like Caterkiller. Originally in Sonic the Hedgehog 2 Crawlton had a dark blue appearance, which may be character design error in the film.
 * In Mega Man X3 there is also an enemy named Caterkiller, but does not bear any resemblance to the badnik.