|Jafar says: Read my lips and come to grips with the reality!|
The Lost Ones are minor antagonists in Bendy and the Ink Machine, more specifically, Chapter 5 and one appears as the deuteragonist in the prequel, Boris and the Dark Survival.
The Lost Ones are tall, thin humanoid figures covered by ink with glowing orange eyes.
Very little is known about their past, but it's implied they were humans once. Though it shows that they may have a connection to Alice Angel because in Chapter 4 when Henry finds them, on the wall behind them, it says 'NO ANGELS'.
Chapter 4: Colossal Wonders
They appear in various locations, like the archives, the room with access to the vents and the research and design area. They're totally passive with the player.
Chapter 5: The Last Reel
They appear in their village. They become aggressive and try to kill the protagonist Henry using Gent Pipes after Tom kills Sammy Lawrence.
They're always sad and frightened. They aren't really evil and want just to be free from the studio. It's possible that in Chapter 5 they get angry with Henry, Allison and Tom because of the death of their boss Sammy Lawrence and that's why they attack them. It's also possible they attacked due to Henry now having a weapon whereas earlier they didn't attack because Henry did not have a weapon and posed no threat.
Bendy and the Ink Machine