Great Zapfish

The Great Zapfish are characters in the SS undefined. They are extremely large Zapfish that power all of Inkopolis and Splatsville respectively. In and  the Inkopolis one is captured, while in  the Splatsville one is captured. To free them, they must be rescued by the player in a single-player mode.

Appearance
Unlike other Zapfish, the Great Zapfish are massive and more similar to the real-life electric catfishes. It has an orange mouth, a peach face, a dark blue body, a small, dark blue tail with lime green along the edges, similarly colored fins, and yellow curled whiskers for Inkopolis' one, or brown curled whiskers for Splatsville's one, that both give off electricity.

Following the events of Return of the Mammalians, Splatsville's Great Zapfish returns to its home, with a new single strand of hair on its head.

Splatoon


The Great Zapfish is a giant animal circling Inkopolis Tower, powering the city. According to the first Sunken Scroll, the Great Zapfish is 100 years old, and powers the entirety of Inkopolis. However, when the player enters Inkopolis Plaza for the first time, an Inkopolis News broadcast states that the Great Zapfish has been stolen and that this event is believed to be linked to the UFO that crashed earlier outside of the city. When the player goes to Octo Valley for the first time, Cap'n Cuttlefish, a veteran of the Great Turf War from 100 years earlier, tells the player that the Great Zapfish has been stolen by the Octarians as an act of revenge for losing the war. Cuttlefish recruits the player so that they can take back the Great Zapfish, but first, the player must take back every regular Zapfish, as these were stolen as well in order to power the Octarian domes.

After collecting all regular Zapfish, the player finds the Great Zapfish in the possession of DJ Octavio, leader of the Octarians, who baits the player into saving it before sucking it up into his Great Octoweapon, the Octobot King. After the player defeats Octavio with the help of Agent 1 and Agent 2, the Great Zapfish is saved and can be found resting on Inkopolis Tower for the rest of the game.

A seemingly unrelated Great Zapfish makes a cameo appearance in the stage Piranha Pit, where it occasionally rises from the water in the background. Embroidery depicting the Great Zapfish also appears as decoration on the Zapfish Satin Jacket.

Splatoon 2
As the player enters Inkopolis Square for the first time, an Inkopolis News report is cast by Pearl and Marina informing everyone that both the Great Zapfish and Callie have gone missing. After the player goes to Octo Canyon for the first time, Marie explains that Callie and the Great Zapfish have been taken by the Octarians. The player is given the Hero Suit and joins the New Squidbeak Splatoon as Agent 4. The player goes through a series of levels, obtaining both regular and mini Zapfishes along the way. After completing all levels, the player must defeat DJ Octavio in a final boss fight. With the help of Sheldon and Marie, the player defeats DJ Octavio and saves Callie and the Great Zapfish. After DJ Octavio's defeat, the Great Zapfish does not return to Inkopolis Tower, but will instead be resting on Deca Tower or on the tracks above Grizzco Industries, or even flying around the sky, producing a barely-audible jingle (the same jingle that plays in the final level of Octo Canyon, Tide Goes Out, when DJ Octavio is sucking the Great Zapfish into the Octobot King).

A Great Zapfish also appears in Piranha Pit and on the Zapfish Satin Jacket just like in the first game.

Splatoon 3
In, when the player first enters Splatsville, a special Anarchy Splatcast broadcast takes place in which Deep Cut reveal that the city's Great Zapfish has gone missing. In Return of the Mammalians, it is eventually revealed that the Great Zapfish was stolen by Mr. Grizz and used as a source of power for his rocket The Spirit Lifter, which he planned to use with the intent of covering the planet in Fuzzy Ooze. It is located in the steerage section. Following Mr. Grizz's defeat at the hands of Agent 3, the Great Zapfish returns to Splatsville, resting on the Battle Lobby Tower, with Deep Cut remarking on its slightly different appearance in another special Anarchy Splatcast report.

Like in the previous games, the Great Zapfish also appears on the Zapfish Satin Jacket.

Trivia

 * Great Zapfish are a species, and not a singular entity, which is revealed through many small details.
 * Throughout Return of the Mammalians, Splatsville's Great Zapfish is never implied to be the same one from Inkopolis, with Shiver Describing it in the Splatcast where it's announced to be missing as "power[ing] the whole city!", and Cap'n Cuttlefish calling it "The Great Zapfish that powers Splatsville".
 * Also in the Splatcast where it's announced to be missing, the image provided shows it with brown whiskers, which shows that they are naturally brown and aren't from Mr. Grizz's experimentation, unlike the lone hair.
 * In Wave 1 of the Splatoon 3: Expansion Pass, Inkopolis' Great Zapfish can be seen looking exactly how it does in the first two Splatoon games, cementing that they aren't the same entity.
 * After the Splatoon 2 version update, many players reported the Great Zapfish missing in Inkopolis Square, even if they had already completed story mode. This was patched in a later update.
 * In WarioWare, Inc.: Mega Microgame$!, there is a minigame called Electric Groove Fish that has an electric catfish move electricity to a city to power it, similar to the Great Zapfish's role.