Player Settings

Upon starting the Splatoon games or selecting "Player Settings" from the Options menu, the player is given a variety of options to customize their Inkling or Octoling.

Splatoon
The player has the option to change the following:

Splatoon 2
Splatoon 2 added the ability to change the player character's hairstyle and leg wear, as well as additional options for eye color. Four new options for hairstyle and four for legwear, two for each gender, were added in Version 2.0.0. Hairstyles and legwear can also be changed in the Equip screen. The Octo Expansion update added the ability to play as an Octoling, after beating the campaign.

Trivia

 * There is a seperate player customization screen in Octo Expansion, having the playable Octolings floating naked in a test tube full of green liquid with lime-green stains across their bodies, being functionally identical to the normal one with only the legwear option omitted.
 * As an added detail, the selected Octoling will appear to "wake up" more and more as they're customized, going from having their eyes shut and being completely still when picking gender, to progressively opening their eyes and looking around as more options are selected, to finally looking at the camera and crossing their arms with a determined expression once their appearance is finalized.
 * In Octo Expansion, it is possible to choose Agent 3's appearance, having the same options as the player customization in Splatoon.
 * In Splatoon, when changing the player customization both Inklings would have the same skin tone and eye color as the recent Inkling the player had. If it's the first time picking a character, then the default Inklings would have the girl with the second lightest skin tone and orange eyes, and the boys would have the third lightest skin tone and blue eyes. Both of these are based on the main Inklings often featured in promos.
 * In Splatoon 2, one of the Inklings and Octolings corresponds to the recent Inkling and Octoling the player had, while the remaining assume their default look. The default Inklings and Octolings have both girls in the middle skin tone and orange eyes, while boys have third lightest skin tone and blue eyes. The hairstyles and looks are also based on the main Inklings and Octolings featured in promotional materials.
 * Additionally, when switching from an Inkling to an Octoling or vice-versa via the Options menu, the game will "save" the player's last-used appearance as the opposite species, which is used for the singleplayer sections. For example, if the player enters Octo Canyon as an Octoling, they will temporarily revert to an Inkling using their previous appearance while playing as one for Agent 4, while entering the Deepsea Metro as an Inkling will use the player's previous Octoling appearance for Agent 8.
 * In Splatoon 2, all character options will have different animations for each section of options, such as the character looking down at themselves when deciding on legwear options, or hunching over towards the camera when picking an eye color.
 * These animations are the same for both Inkling genders, but vary between Octoling genders.