Alternate names: Nameless, No-Name, The Nightmare of the Labyrinth
Kumoko (蜘蛛子) is a fan-made nickname for the main character of Kumo desu ga, Nani ka?, who had remained canonically nameless for a long time.
Kumoko's identity in the story is unknown at first (in the original web novel and light novels, even her gender is initially unknown), and any hints at her identity are therefore spoilers and should be marked as such. She reincarnated after dying in a mysterious explosion in her high school literature class in the form of a spider within a monster-filled labyrinth and with gaps and inaccuracies in her memories of her original life, including her own name, and finds herself having to do everything she can just to survive.
Remember that "Kumoko" is the name of the spider character, and images that do not possess a spider form should not be tagged "Kumoko" to reduce needless spoilers. Her hybrid arachne form unavoidably becomes a spoiler, and all images in her arachne form should be tagged as spoilers.
She has an extensive page in the Kumo Desu Ga Wiki