The Librarian is a recurring NPC who briefly appears each time the Drifter interacts with a monolith. Though the Librarian herself cannot be conversed with, the monoliths she activates are the most substantial sources of written text in the game.
As with a majority of the characters in Hyper Light Drifter, the Librarian is given neither a canon name nor gender in the game. "The Librarian" has previously been used by the game's developers when discussing the character; similarly, the developers generally use female pronouns when referring to the character.
The Librarian is humanoid in appearance; she has white eyes and gray skin, and she wears a light blue beanie, a pair of orange goggles, and an ochre-colored cloak. Like the Drifter, the Librarian has her own companion bot, which can be seen projecting yellow holographic tablets in front of her.
Whenever the Drifter interacts with a monolith, the Librarian appears for a very brief period of time in a seemingly holographic form, flickering during a brief animation in which she can be seen looking between the monolith and her own holographic tablets. After a few seconds, as soon as the text glyphs are displayed on the monolith in full, the Librarian promptly disappears; she is not seen again until the Drifter interacts with a different monolith.
The Librarian's cloak, her companion bot, and a sword can be found inside of a locked glass display case in the Monolith Gallery. After the Drifter finds and activates all 16 monoliths, the case is unlocked, giving the Drifter access to the Librarian's equipment. Equipping any combination of the Librarian's equipment grants the Drifter an additional square of health. Activating all 16 monoliths also awards the Librarian achievement and causes a large block of text to appear on the wall in the Library.
After all 16 monoliths have been activated, the Librarian never again appears during the same playthrough.
The Librarian has been described by the developers as a "peaceful, nonviolent Drifter" who is a "different kind of drifter" than the protagonist, wanting only to "travel, study, and observe".
She is also confirmed to be "afflicted with the same problems as The Drifter, but used her time differently"--suggesting that she had the same illness, but did not pursue a cure, using her time to instead travel the world.
It is not confirmed, but judging from her name and her role in the story, she is both connected to the Library, as well as the paragraph of glyph text that appears on the wall after all 16 monoliths are activated.
-Librarian; Unlocked after activating all 16 monoliths.