Graffiti characters

From Inkipedia, the Splatoon wiki

Jr. Mark

Jr. Mark comes in both squid and octopus version, and has many different color variations.

The color scheme comes from wakaba mark, or Beginner Drivers' Sign, which are used to mark beginner drivers in Japan.

Splatoween
FrostyFest
SpringFest
Summer Nights
Final Fest
Grand Festival

SQDLD/FLDRHTS-OKTBY

These characters appear as graffiti and stickers in many Splatfests.

Climbing Skipjack tuna

This fish is the official mascot of Octo Canyon.[1]

ASARIDEAD

This character was created by graffiti artist Sally.[2]

Lampion fish

This fish has variations for special Splatfests in Splatoon 2.

Splatoween
FrostyFest

3TSCRM

This character has variations for Splatfests in Splatoon 3.

TNBYT

This fish is seen for Splatfests in Splatoon 3.

More

Splatoween
FrostyFest
SpringFest
Final Fest