The White Hot Room is a realm that serves both as the afterlife and a base of operations for the Phoenix. The White Hot Room also resides in the M'kraan Crystal, which is a nexus of realities and contains a Neutron galaxy.
When Jean Grey first bonded with the Phoenix and later sought to heal the M'Krann Crystal she found a white city inside. She felt as though she were connected to it and was meant to heal it. 
Later, when Jean Grey appeared in the afterlife and met Death and his towers, Death described the realm as "the alpha and the omega, the beginning and end of all-- where the physical universe merges with the domains of the spirit and imagination." When beings die they go inside Death's towers, but the Phoenix exists outside of the towers to do her work. During the second encounter with Death and the afterlife, Death explains to Jean that his towers are compartmentalized and that all beings go there to experience their own version of the afterlife.
When Quentin Quire briefly ascended to the White Hot Room as he was near death, he could hear and understand the thoughts of everyone on Earth, and he realized that he had met his parents there before he had been born.
Jean Grey would later comment that we are all in the White Hot Room waiting for ourselves to arrive. When Jean went to the White Hot Room as The White Phoenix of the Crown to disinfect Sublime, the Phoenix Consciousness explained that the White Hot Room is inside the M'Krann Crystal. It is a hospital to the universe and where Phoenix Work is done. Jean met various Phoenix hosts in the White Hot Room.
The White Hot Room is also where a Phoenix-like Jean Grey may go if they do not instantaneously resurrect when killed, and do Phoenix Work while they await to incubate and be reborn anew from a Phoenix Egg.
Inside the White Hot Room is the Crown. Several times Jean spoke of being in the Crown, and the Phoenix Consciousness labeled her a White Phoenix of the Crown. However, it has yet to be explored as to what the Crown actually is.
During the House of M event, Psylocke and Rachel Summers would be pulled into the White Hot Room by a holoemphatic crystal, that Jean Grey had left for Rachel, to temporarily protect them from the effects of Scarlet Witch's powers. Rachel refers to the White Hot Room as the Heart of the Phoenix. In the White Hot Room, Psylocke encounters alternate universe versions of herself, while Rachel only encounters herself in different time periods of her life.
In recent times Jean Grey and the Phoenix were pulled from the White Hot Room and separated and shattered. Upon coming back together, Jean has faded away to the White Hot Room as White Phoenix to collect the rest of the missing pieces of the Phoenix. She made contact with Cyclops when he became the Dark Phoenix, and tried to help him to control the Phoenix Force.
The White Hot Room has recently been referenced by the former Avenger Sentry (now a Horsemen of Death), who stated that the Void and Exitar the Executioner are both currently residing in the realm.
- Jean Grey
- Phoenix Force
- Jean was seen taking her family into the White Hot Room in End of Greys, making them presumable residents.
- Other past and future host that are not named.
- The Void
- Exitar the Executioner
- Jean Grey seemingly ushered her family into the White Hot Room after they were slaughtered by the Shi'ar Death Commandos.
- Wolverine had a near death experience in which he had a vision of Jean dressed in a white gown bathed in white light. Jean comments that they are near the entrance to the afterlife, and that she had been there so many times that she has left a piece of herself at the door.
- In the X-Men: The End miniseries, the Stepford Cuckoos refer to Jean as Phoenix as living in the Center of Creation.
- The existence of this location is known to Jean Grey, Quentin Quire, Phoenix Corps, Death, Psylocke,, Rachel Summers, Cyclops Jane Foster  and the Sentry.
- 12 appearance(s) of White Hot Room
- 2 minor appearance(s) of White Hot Room
- 6 mention(s) of White Hot Room
- 4 image(s) of White Hot Room
Links and References
- X-Men #108
- Classic X-Men #43
- X-Men Forever #3
- New X-Men #138
- New X-Men #151-154
- X-Men Phoenix Endsong #1-5