The Phoenix Witch is the representation of death and a mythic in the Killjoys comic series, serving in a similar capacity to the Grim Reaper.
The desert is fairly divided as far as belief in the Witch. The Ultra V's mention that Val does not believe in her because "he doesn't believe in anything he can't shoot", while Vaya and Vamos do not seem to sway in either direction. The Girl had originally believed in her as a child, but eventually didn't as she grew up. She was convinced after a conversation with Cherri Cola.
The Girl meets with the Witch during an out-of-body experience. She is medium height with very thin arms and legs wrapped in deep red ace bandages. The rest of her body is completely covered in what appears to be thick black fur like a yak's, with large feathers and a painted hockey mask obscuring her face. The Phoenix Witch takes care of the dead when its their time to go, though offerings of anything "close to the soul" of a dead person help her guide them to their proper destination. She collects offerings from a postbox and also gathers them after battles with a shopping cart.
She has a very straightforward personality, telling The Girl about her mother's past history with the Killjoys and her power. She also has past history with Cherri Cola, though she doesn't specify beyond it being "a long time and a different world ago".