Octarian

The Octarians are a race of octopus creatures and the main antagonistic species of the story mode in Splatoon. They reside in Octo Valley and Octo Canyon, and are responsible for stealing Zapfish from Inkopolis. Their main ink color is purple/magenta. At one point the Octarians were a neutral species coexisting with Inklings, but this ended as result of conflicting interests of territory that lead to the beginning of the Great Turf War (in which the Octarians lost).

Unlike Inklings, the species includes a great amount of sub-species that act differently from each other. Like Inklings, certain Octarians can switch between mollusk form and humanoid form at will.

Known Octarians

 * DJ Octavio (Leader)
 * Marina (Octoling, member of Off the Hook, and Show Host)
 * Agent 8 (Octoling)
 * Dedf1sh (Sanitized Octoling)

Types of Octarians

 * Octotrooper
 * Shielded Octotrooper
 * Octodiver
 * Twintacle Octotrooper
 * Shielded Twintacle Octotrooper
 * Deluxe Twintacle Octotrooper
 * Twintacle Octodiver
 * Octocopter
 * Deluxe Octocopter
 * Octoball
 * Octosniper
 * Octobomber
 * Deluxe Octobomber
 * Octostamp
 * Octostriker
 * Octohurler
 * Octoseeker
 * Octozeppelin
 * Octomissile
 * Octoling
 * Tentakook
 * Octocommander
 * Octoballer
 * Sanitized Octarian

Machines

 * Squee-G
 * Industrial Squee-G
 * Flooder
 * Octopod
 * Octorpedoes
 * Octostamp DX
 * Ink Piston

Great Octoweapons

 * The Octostomp
 * The Octonozzle
 * The Octowhirl
 * The Octomaw
 * The Octobot King

Octobosses

 * Octo Oven
 * Octo Samurai
 * Neo Octostomp
 * Octo Shower

In the manga series
In the end of the fan-made issue of Splatoon, a then unnamed Glasses-Kun flies over a bunch of Octotroopers and Octoballs. They appear again in the Hero Mode issues, when Glasses and Rider are enlisted by Captain Cuttlefish to recapture the Great Zapfish.

Trivia

 * According to the first artbook, lower-ranked Octarians aren't able to reproduce on their own and thus are created by cutting off a tentacle from a host. Their intelligence are linked to how many limbs they have, and high-class Octarians usually grow more limbs. Both the playable and enemy Octolings are considered a separate species from the lower troops, and presumably have full reproductive capabilities and intelligence as well.
 * The bassist of the Chirpy Chips is an octopus, but has never been connected to Octarians and bears little resemblance to Octarians seen so far.