Octoling

Octolings are playable characters in Splatoon 2 and, alongside Inklings. In Splatoon 2, Octolings are only available after beating the Octo Expansion DLC, unlike Inklings, which are available from the start. In Splatoon 3, Octolings are available from the start like Inklings are.

The player can switch between Inklings and Octolings in the Player Settings. The game will save both the player's Inkling and their Octoling simultaneously, likely due to single-player modes where only one of the two is playable.

Background
The playable Octolings were once fighters in the Octarian military, brainwashed by the music of DJ Octavio, but when they heard the Calamari Inkantation, it nullified the brainwashing effect, freeing their souls from the oppression. Many (but not all) of them escaped to Inkling society in Inkopolis afterwards, hoping to start anew. This happened during the "Enter the Octobot King!" mission of the first game.

Appearance
Like Inklings, Octolings can switch between a humanoid form and an octopus form.

Their octopus form is widely different to the Octarian ones, with two long tentacles in the middle that helps them move, two smaller ones in front that resembles a mustache, and four smaller ones on the underside, along with a pair of eyes that are separated and resemble an Inkling squid's eyes. The suction cups are located on the underside of their tentacles, as opposed to their humanoid form having suckers on the top side. The tip of their tentacles, as well as the head, have a ring pattern on them. They have a total of eight tentacles.

The humanoid form has black markings around their eyes, with both genders having two sharp edges and a thicker underline, where the female Octoling has an added dash to their markings. Octolings do not have their markings connect over the middle, having it seperated compared to Inklings. Their teeth are also different, having one sharp end tooth on their left side on the top, and another sharp tooth on the right side on the bottom. Their ears are round and asymmetrical, with the right side being flat and the left side being indented, each respectively resembling the fin and siphon on an octopus. Similar to enemy Octolings, the end of their fingers are semi-sharp, but the playable Octolings do not have these ends being tinted in their ink color. Their eyebrows are also different from Inklings, with males having a half oval shape and females having a curved droplet shape.

Just like Inklings, Octolings are able to choose from a variety of skin tones, hairstyles, and eye colors. The choices of eye color and skin tone are identical to the Inklings. Both the male and female Octolings possess two different choices in hairstyle. The female Octolings' first hairstyle has two thin tentacles in front reaching past their shoulders and two thicker, shorter tentacles in the back, all with curled tips. Their second hairstyle has two tentacles tied back into a ponytail, with the other two as sideburns. The male Octolings' first hairstyle features a mostly shaved style, with one large, curled tentacle and three smaller tentacles lined up along their head to create a mohawk (The mohawk design might be a reference to the Octotrooper tentacle). Their second hairstyle is an afro reminiscent of an Octopus' mantle. This hairstyle notably molds while wearing headgear.

Some Octolings (namely Marina) have special features, such as a plum color on their tentacles, and brown pupils shaped like the infinite logo. Playable Octolings, like their enemy counterparts, have sharper nails than Inklings; Marina's are colored teal, which is another special feature for Octolings.

Octo Expansion
The Octo Expansion introduces the mysterious Octoling character Agent 8, and will allow players to use Octolings in multiplayer upon completing its story mode. The male version of Agent 8 is also the first appearance of a character which is clearly shown to be a male Octoling in-game. Their octopus form is more reminiscent of the squid form of Inklings, with a key difference being that their eyes are separated instead of together.

When the player completes the Octo Expansion, they will be able to change from being an Inkling to an Octoling in the player settings. Playable Octolings have different animations for trying on gear, winning or losing, and for taking photos with amiibo. The Squid Research Lab Tumblr showed that Octolings are more serious than Inklings and have an interest in technology. For example, instead of aiming with weapons, they will look more closely at them to see how they work, they wave around their phones and look at them more closely, and their icons in battles are not seen smiling. Due to have been defecting from the Octarian army, their animations around the Square make them look curious and almost confused.

While both types of characters are called "Octolings" in English material about the Expansion, the Japanese version makes a notable distinction between the player Octoling, called "Octopus" (タコ Tako), and the enemy Octolings, called "Octopus-Amazon" (タコゾネス Takozonesu). The latter specifically refers to the older elite female unit that only a select few of the former can become.

Trivia

 * When an Octoling is splatted, they will fly off in the form of a small ghost, just like Inklings. They have their own unique octopus ghost for this.
 * This difference extends to other graphics, such as the weapon and status indicators, splat messages, and splatted enemy markers having a small cartoon octopus instead of a squid.
 * Playable Octolings are represented by pink ink in the Player Settings menu, while Inklings use green ink. Before being added, Inkling boys were green and Inkling girls were pink.
 * After Octolings are unlocked, the Player Settings screen has octopuses swimming up with the squids in the background.
 * Unlike Inklings, the Octolings' genders have different animations in the Player Settings.
 * Octolings' smartphones are different than Inklings', and have a round shape, similar to an octopus' head.
 * Octolings in Inkopolis Square have different movements than Inklings. Notably, the ones with phones show confusion when trying to use them and the girls tend to demonstrate a shyer demeanor.
 * The Octolings seem to take losing badly in comparison to the Inklings, as shown in their winning and losing animations, with many of them falling on the ground in disappointment, the boy shaking his fist, and the girl crossing her arms. Additionally, when they win, they tend to strike poses, in comparison to the Inklings jumping for joy.
 * The playable female Octoling model appears to not be as curvy as the hostile Octoling model.
 * Octolings are prohibited from entering Octo Canyon. Instead, the game automatically switches back to the previous Inkling used, customization options included, since that character would canonically be Agent 4. Similarly, the opposite happens when entering the Deepsea Metro as an Inkling.
 * In the Squid vs. Octopus Splatfest, players on Team Octopus had their avatar switch to Octolings when inside battles, even if they did not have the Octo Expansion. In Inkopolis Square, the avatar remained unchanged. The reverse was true for Team Squid.
 * As seen in the Squid vs. Octopus Splatfest, the Splatfest pictures stylize an Octoling's eyes as separated as opposed to Inklings' eyes being together conjoined.
 * In The Art of Splatoon, they were originally going to have Inkling masks and floppy ears like a dumbo octopus. The ideas were discarded except for the curly, above-suckers hair and armor.
 * However, the rounded ears may have been reintroduced in Agent 8's design and the design of the playable Octolings.
 * The playable Octolings reveal that there are male Octolings in the Octarian army.
 * A Splatoon 2 Anniversary Famitsu interview with the developers revealed more information about Octolings:
 * Octolings were considered to be playable during the start of Splatoon 2's development, but they wanted an explanation as to why they are playable and to have the player empathize with them along with the new band, Off the Hook, which led to the Octo Expansion being made.
 * In an interview prior to this, the developers revealed that they did consider playable Octolings in the first Splatoon, even before hackers modded enemy Octolings to be playable.
 * Octolings that are not Agent 8 found other means and routes to get to Inkopolis, similarly to Marina.
 * Due to the Inklings' easy-going and inattentive nature, they did not notice the Octolings' arrival.
 * They are slightly younger than the enemy Octolings, and the explanation for no male enemy Octolings appearing is due to only the elite female ones being able to become Octoling soldiers fought in the single-player campaigns.
 * Splatoon 2's art director, Seita Inoue, wanted the afro to be the default hairstyle for male Octolings. There even appeared to be concept art for the female one having an afro.
 * Concept art of Salmon Run in The Art of Splatoon 2 show both Inklings and Octolings fighting together against early versions of the Salmonids, reconfirming that Octolings were planned to be playable from early on.
 * Early models of the playable Octolings have been found as early as the Splatoon 2 Global Testfire, where the male Octolings have a hairstyle close to the final "Punk" one, while the female model uses the enemy Octoling hair. The models were deleted in the release version of the game, but entries for the player model type still exist in Version.
 * Hackers modded Octolings to be playable shortly after Splatoon's release, albeit reusing the enemy model.
 * Some, although not all official artwork feature the playable Octolings having their fingertips colored in their ink color; though this feature is lacking in their in-game model. This feature is reminiscent of Marina's fingertips being colored in her ink color as well as all enemy Octolings who also have their fingertips colored both on their in-game model in Splatoon 2 and shown in concept art in the The Art of Splatoon 2. This suggests that colored fingertips might be a general feature that Octolings are capable of having.
 * This may be a feature only fully mature Octolings possess.
 * Oddly, in some official art, Marina lacks her colored fingertips, or they are only colored on the palm-side.