Octostomp

"I'm BAAAAAAAAACK!"

- The Octostomp at the beginning of Lips for Days mission.

The Octostomp is one of the Great Octoweapons encountered in Octo Valley, later reappearing in Octo Canyon and the Octo Expansion.

Background
The Octostomp was an Octoweapon created during the Great Turf War by the Octarians. When it seemed that victory had smiled upon the Octarian army, a plug was pulled and caused the Octostomp and the rest of the Octarian mechs to shut down. Nearly 100 years later, the Octostomp was brought back to life by the power of a Zapfish to attack once again.

Appearance
The Octostomp is a robotic Octarian in the shape of a large cube with several layers on its Octotrooper-like face covered in dripping purple ink, with many elements appearing recycled from other sources. He has nine panels on all sides other than the underside, front, and the back. These panels vary between simple metal plates and asphalt, featuring yellow pavement markers and bike lane indicators. Similarly, the underside to which the legs are attached is visually identical to some floating Octarian platforms that appear throughout Octo Valley, retaining the flashing light pattern. The back plate features a hole from which the controlling tentacle emerges to grab Zapfish, and when faceplanted. He also has two legs that are thin and short in comparison to his size, but strong enough to allow him to jump high. In the second game, he is given an ink-proof jacket that appears to be made of thermal fabric, along with a rubber belt, overall resembling an insulated food bag.

Splatoon


In Octo Valley, the Octostomp is the first boss Agent 3 encounters. He appears in the mission The Mighty Octostomp!, where Agent 3 has to dodge his attacks (which are him slamming his face into the ground) and climb up his body to splat the tentacle. After each phase, several panels from the side are removed, and in the third phase, the panels will begin moving, making it harder to climb. Once Agent 3 has splatted the tentacle the third time, the Octostomp will be defeated and explodes.

Octo Canyon


In Octo Canyon, the Octostomp comes back as the third boss in his eponymous mission Lips for Days, where this time he comes with a few more tricks up his sleeve. The first phase plays out as it did in Octo Valley, where Agent 4 must dodge him and then climb to his back to splat the tentacle; however, he does have a new attack in which he rushes forward before smashing his face down. In the next phase, he gains an uninkable coat with a belt around him and is called the "Neo Octostomp" afterwards. Agent 4 must destroy the buckle to remove the coat in order to climb his sides. Additionally, an Octotrooper with a Splatling-esque machine gun is seated on top of the Octostomp, firing ink at the ground at a rapid rate. Unlike the Octocommander, the machine gun does not appear to have a windup time and its fire rate does not become faster as it continues. In the third phase, he once again uses the coat, but now has two extra faces, making his attacks more difficult to avoid. After the third tentacle has been splatted, he explodes, just like last time.

Octo Expansion


The Octostomp also appears in the Octo Expansion, where he has been Sanitized and renamed "Octostomp Redux". He now resides in Drop the Bass Station, where he can be battled. The boss battle is very similar to the one in Octo Canyon, with the ink-proof coat and the Splatling-esque machine gun-wielding Octotrooper on top of the Octostomp Redux, but there are differences. The Octostomp Redux has the ink-proof coat for all three phases instead of the last two, and once the coat is broken, three sanitized bubbles, similar to those created by the Bubble Blower, are blown from the Octostomp Redux's climbable sides whenever he smashes onto the ground, which makes climbing his sides slightly harder.

Once Agent 8 has splatted the tentacle enough times, Octostomp Redux will be defeated and will, like always, explode.
 * In the first phase, the Octostomp Redux has an ink coat with one buckle on the front. The machine gun-wielding Octotrooper does not appear and the Octostomp Redux does not blow bubbles from his mouth, but he still blows them from his sides whenever he smashes onto the ground after the coat is broken.
 * In the second phase, the ink coat has two additional buckles on the sides. Starting from this phase, the machine gun-wielding Octotrooper can pop up from the Octostomp Redux's top whenever his ink coat is up and he can blow two bubbles (similar to the Bubble Blower) from his mouth, which can be popped by the Octotrooper to cause a chain explosion.
 * In the final phase, the ink coat has two extra faces, each of which has a buckle (for a total of three buckles) and can blow two bubbles (for a total of six bubbles per blow), which can cause a larger chain explosion should they be popped by the machine gun-wielding Octotrooper.

Return of the Mammalians
While the Octostomp does not make a direct appearance in Return of the Mammalians, an Octostomp's remains have been found and repurposed by Frye as a nest for her moray eels. They are fought in the mission The Future Stares Back. The Octostomp's eye-sockets are empty, but it still makes Octarian noises when getting hit by the moray eels. This version seems to be based upon a self-balancing cube, with one of the fans visible where the tentacle once was.

Trivia

 * The Octostomp and Marie are the only characters to appear in some way in all four of the single-player campaigns, not counting cameos. If one does count cameos, then Callie, DJ Octavio and Agent 3 also count, as the former two can be seen in images in Marina's chat room in the Octo Expansion, and the latter appears in the Sunken Scrolls in Splatoon 2's Hero Mode.
 * This only applies to the Octostomp if one considers the hollowed-out Octostomp shell that Frye uses to still be the Octostomp character, rather than a lifeless tool.
 * The Octostomp and DJ Octavio are the most fought bosses in the Splatoon series, being fought three times each.
 * If one counts the remaining shell, the Octostomp is the most fought boss instead.
 * Octostamps, Octostamp DXs, and Octoseekers all appear to be based on the Octostomp.
 * Despite being Sanitized, it is implied that the Octostomp Redux remembers his prior battles when he says "Back like I never left".
 * The Octotrooper operating a Splatling-like machine gun does not resemble the other Octarian fighter that uses a Splatling, the Octocommander.
 * The Octostomp is the only boss to have two introductions in a single battle. This happens in Lips for Days in, with the second introduction happening at the start of Phase 2, where it is renamed to Neo Octostomp.