Dark Phoenix

Dark Phoenix is the name given to Jean Grey after she became corrupted by the Hellfire Club and turned into a vastly powerful supervillain who proceeded to cause chaos across the universe until being defeated in a battle that supposedly claimed her life (of course Jean Grey was later revealed alive) - although modern retelling attribute much of the events to the corruption of the Phoenix-Force in the original comic book (and ) the Dark-Phoenix was simply Jean Grey gone bad rather than a separate/merged entity.

The Phoenix, in the form of Jean, appeared as the primary antagonist of X-Men: The Last Stand and a prominent plot point in the final episodes of Wolverine and the X-Men. Dark Phoenix was also used in the 1990's X-Men cartoon's third season. She was portrayed by actress in X-Men: The Last Stand who also portrayed Xenia Onatopp, Evelyn Stockard-Price, Rachel Wright, and Muriel, and by Sophie Turner in X-Men: Apocalypse, and soon Dark Phoenix.

Backstory
Jean Grey was a child who always thought she was normal human being. At the age of 10, she witnessed the death of her best friend Annie Richardson, who got hit by a car. The emotion caused by the accident awoke in Jean powerful mutant psychic powers such as telekinesis and telepathy, allowing her to feel her dying friend's pain.

As Charles Xavier recuited her in his X-Men team, she endorsed the code name "Marvel Girl" (a nod to the company the character belongs to). He trained her to control telekinesis, but supressed her telepathy during a long time, only to teach her how to use it as she was more mature, so she wouldn't suffer from trauma. She is one of the founding member of the team.

The Phoenix Saga
During The Phoenix Saga, the X-Men were caught in a solar storm, as they were aboard a spaceship. Jean used her telekinesis to protect her team and herself. However, her psychic barriers weren't strong enough to hold back such power. She miraculously survived thanks to the help of the Phoenix Force, a cosmic entity of God-like power which has control over life and death, that found a host in Jean Grey. She awoke in the ocean, calling herself "Phoenix" in front of her teammates. She gained powerful pyromancy powers that water can't even drown, which often appears around her in the shape of a firebird.

Having so much power in one's hands created jealousy towards the X-Men. The Hellfire Club, a group of psychic villains such as Emma Frost, began to manipulate Jean, and eventually kidnap her and hid her from Xavier and Cerebro. The group altered her mind, causing her to think she is part of them, their Black Queen. Later, when she was saved by the X-Men, Phoenix realized that she was manipulated, the psychic scheme of the Hellfire members left her mind bruised. The Phoenix Force whithin her took the opportunity to gain control of her body, and she became the Dark Phoenix : a energy-hungry being which seeks to destroy the universe in order to gain more power. She turned against her own team, thus starting ''The Dark Phoenix Saga. ''

The Dark Phoenix Saga
During the said story arc, Dark Phoenix caught the attention of the Shi'ar Empire (whose Empress Lilandra was Charles Xavier's lover) by consuming a star's energy, which caused it to go supernova, destroying planets and countless alien civilisations around it. Later, she even destroyed herself a Shi'ar spaceship and the crew aboard. The Empire immediately classified Jean Grey as a threat for the universe and went at war with the X-Men. During their last fight on the moon, Jean regained control of her own body. Aware that nothing or no one could stop her if not herself, she triggered a Shi'ar laser canon with her telekinesis and let it desintegrate her.

X-Factor
Later, the Fantastic Four discovered in Jamaica's Bay (where the X-Men's spaceship crashed as Jean became Phoenix) a cocoon holding a humanoid body. DNA test proved that it was Jean Grey, who was put to sleep the whole time, and that the one becoming "Dark Phoenix" was in fact a clone. She joined X-Factor along the first members of the X-Men.

Grant Morrison's New X-Men
But unfortunately, the Phoenix Force rose again in the shadows. Jean embraced it during the New X-Men events, manifesting pyrokinetic auras and strong psychic energy. With its help she managed to resurrect Emma Frost, who was broken into several little pieces. She faces Cassandra Nova, Charles Xavier's evil twin sister, in order to prevent her from using Cerebra as a weapon to eliminate every mutant on Earth. But she eventually is killed by Xorn, caught in a persona dilemma with Magneto, who sends a planetary-sized electromagnetic wave right into her body. Jean dies since The Phoenix Force is unable to heal in time the stroke she is having because of this attack.

Phoenix : Endsong
The Shi'ar Empire found the Phoenix Force, way later, in a sleep-like phase. They proceeded to destroy it for good, only to awake it in the end. The Phoenix fled towards Earth and entered Jean's dead body, reviving her and forcing her to crawl out of her own grave. After that her powers over life and death healed her wounds, Dark Phoenix didn't wait long before showing up again. The entity was seeking for the essence of love that Scott used to give to its host. Unable to embrace this feeling, it was in fact seeking after energy, such as the one coming from Scott's force vision, in order to empower itself. During a fight between the X-Men and The Phoenix at the North Pole, Emma Frost (who is then a member of the X-Men) used her power to show Phoenix how much she was loved, casting an illusion of all the X-Men she knew and their memories of them, saying altogether "Jean." Full of joy and love, Jean has then found the strength to take control of the Phoenix Force, thus allowing her to discover that they were both bounded forever, a part of each other.

Jean Grey became a being life no other, the White Phoenix of the Crown, in a higher state of life. She is one with the Phoenix, and the Phoenix is one with her. Her task now is to find pieces of the Phoenix that scattered all across the omniverse. After telling her beloved Scott goodbye for the last time, she vanished into the White Hot Room (sort of a parralel dimension where the WPotC belongs to) and was presumed dead. She has taken fragments of the Phoenix which where hidden in her daughter Rachel Grey and the Stepford Cuckoos and has been presumed dead afterwards.

Marvel Now!
The fact is that she is not. She even helped Emma Frost, in one of her visions, from being neutralized by the Sisterhood of Mutants. In her last appearance since, Jean told Emma "Well then, little spirit. Prepare." meaning that Jean, as the Phoenix, might come back sooner than we think, more powerful than ever before, holding all the pieces that she had lost. Nobody has seen her after that.

Rumors among fans say that she managed to give birth to her own child by using the immense power from the Phoenix Force. "Her" child would later be raised by her alternate-reality son Cable, and become the Mutant Messiah : the first mutant born after M-Day (an obscure event caused by Scarlet Witch, erasing or depowering most of mutantkind out of existence), her destiny remaining unknown - she could save both mutantkind and mankind as well as she could become an evil entity that would put both sides at war once again.

The Phoenix Force, in a less powerful form, came back recently during the events of Avengers vs X-Men, trying to get control of Hope Summers. An accident caused by Iron Man caused it to split in five parts, which found hosts in Magik, Colossus, Namor, Emma Frost and Cyclops : The Phoenix Five. The last of them found a way to gain the others' phoenix powers and became the Dark Phoenix. Eventually, he killed his mentor Charles Xavier, and depowered from the cosmic entity by Hope Summers and Scarlet Witch, was put in a cell.

In the story arc All New X-Men, the Beast brings back the five original X-Men in the present in order to achieve Charles Xavier's dream - peace between Humans and Mutants - and to prevent tragic events that happened during the team's history. The young version of Jean Grey has one mission, to avoid her older self's corruption by the malevolent Phoenix Force. During their adventures, the young X-Men were sent in space among the Guardian of the Galaxy in order to save their red-headed friend from the Sh'iar Empire, which was ready to sentence her to death for the Dark Phoenix's genocide. Eventually, she manifested the full extent of her psychic power by combining both her telekinesis and telepathy : her body would glow pink, emanating mental energy. This form would enable her to use both powers at the same time in order to use devastating attacks.

Marvel's Legacy and ResurrXion
Along the ResurrXion storyline, the young Jean Grey had to face her own demons. Struck by a vision of the Phoenix Force coming back for her, she manages to get the help of previous Phoenix hosts (Rachel Grey, Hope Summers, the Stepford Cuckoos, Quentin Quire, and even her former archenemy Emma Frost), as well as various other heroes (Namor, Psylocke, the Unworthy Thor, Doctor Strange and Scarlet Witch).

Following her visit at the Sorcerer Supreme's, she is haunted by the ghost of her old self, trying to save her from her own tragic story. In the end, Jean has to face a Phoenix Force that wants her out of its way. The entity engulfs her in flames and kills her, only for her to appear in its dimension, the White Hot Room. During her travel in it, the young Jean is faced by the essence of many past phoenix hosts, transported from prehistory to her first day at Xavier's school. Eventually, she faces the Phoenix itself, which has been trying to get rid of her from its homeworld. Being its true host, she manages to force it to send her back to Earth-616. Once resurrected, she discovers that her older self is alive and what was the real plan the Phoenix Force had in mind.

X-Men : Phoenix Resurrection
In fact, the Phoenix had created an "egg". It was a psychic dimension hidden on earth, creating the perfect life for Jean - featuring elements from her life, such as her husband Scott Summers, her parents, Wolverine, but also her bestfriend Annie who appears to be still alive. While the entity was trying to smolder Jean in order to resurrect her and use her body as a vessel again, her sub-conscious would send the X-Men hints in order to save her - illusions of dead X-Men members, sources of immense psychic power emanating at different points on the planet, paranormal events... It is Old Man Logan that meets her in person, enabling her to dissociate from the reality that the Phoenix made up in order to restrain her. In order to keep her for itself, the Phoenix even resurrects Scott, who she eventually kills after kissing him by absorbing his vital energy, claiming that they were "better off dead". In the end, Jean convince the entity that the Dark Phoenix isn't her real self and that she isn't made for its apocalyptic destiny. Warning that without its presence Jean would die, it disappeared like a flame being extinguished.

After the event of Phoenix Resurrection, Jean Grey joined the X-Men, forming its third team : Red (along the orignals Blue and Gold). Together, they must fight the infamous Cassandra Nova, who is menacing the peace between mutantkind and humankind that Jean is desperately trying to maintain by advocating for her people's rights.

As for the Phoenix Force itself, it has currently not found a new host.

X-Men: The Last Stand
Dark Phoenix is the secondary antagonist in X-Men: The Last Stand - this time caused by Jean apparently going insane. In the film, Professor Xavier recognizably remembered this alternate personality of Jean Grey by its other name "The Phoenix", whom he sees as in his own words, "a creature all desire, joy and rage". In this reality, the Phoenix isn't the name of an evil entity from the space, but an alter ego that the professor had maintained in chains during most of her life.

X-Men: Apocalypse
At a point in the movie, Jean is shown having a nightmare, in which she has a reddish vision of Earth being ravaged by a mysterious cataclysmic event, causing the end of all life. While talking to Xavier in the same scene, she refers to a "dark force" within herself, obviously refering to the Dark Phoenix.

During the movie's climax, she eventually uses her pyrokinetic power in order to stop Apocalypse from nearly killing the Professor. Before being disintegrated, the villain says that "All is revealed." while facing Jean and her firebird aura.

Dark Phoenix
Dark Phoenix will appear as the titular main antagonist in Dark Phoenix.

X-Men: The Animated Series
Dark Phoenix also appeared in the animated series X-Men, in its third season as the main antagonist. In this series, the ending of the Phoenix story arc shows Jean Grey, as Phoenix (still as a fiery creature), taking the super-powerful M'Kraan Crystal into the core of the Earth's yellow sun. Oddly, both survived this and were eventually brought to Muir Island, where Phoenix was developing a darker side that Xavier was understandably scared of. Phoenix would refuse to abandon Jean's body, which leads to her getting captured by the Inner Circle (Hellfire Club) and mind-controlled. Dark Phoenix emerged and broke free of the Inner Circle's control, going into space to destroy a star that was monitored by Shi'Ar explorers. Shi'Ar queen Lilandra goes to Earth and demands that the Dark Phoenix be executed due to it being able to destroy "all that is", just like the M'Kraan Crystal that spawned it. The X-Men have to battle the Shi'Ar's gladiators to save Jean, but when her powers become dangerous, she uses a Shi'Ar space cannon to kill herself. Phoenix emerges and, with the X-Men's life-force, resurrects Jean and leaves.

Wolverine and the X-Men
The Phoenix is featured as a major antagonist in the TV series Wolverine and the X-Men. In this series, the Phoenix is a creature that has been around on Earth since homo superior first appeared. It would enter the host mutant at birth, grow within it and then reach maturity, at which point it would cause mass destruction and risk total destruction of Earth. At the start of the series, a mysterious explosion occurred at the X-Mansion that presumably killed Jean Grey and Professor X.

A year later, Magneto finds a comatose Professor X on the shores of his kingdom of Genosha. The Professor is brought back to the X-Mansion, where the Professor reveals that the coma he is in will last for 20 years and he has woken up to see a world ravaged by fire and the robotic Sentinels are making mutants an endangered species. The cause of both the explosion and the fires on Earth were revealed towards the end of the series, when Emma Frost and Cyclops look at the X-Mansion before it is destroyed; both were caused by stress from Jean Grey, the unfortunate host of the Phoenix, who would unintentionally unleash her powers.

In "Shades of Grey", Jean Grey (who has recently woken up from a coma in a hospital) is ratted out to the Mutant Response Division, who comes to capture her. The Phoenix suddenly manifests and unleashes a psychic wave that causes a portion of the East Coast to lose consciousness. Cyclops and Emma save Jean from Mister Sinister, who uses her Phoenix powers to defeat him. Emma brings Jean before the Inner Circle and tells Jean of the Phoenix, what it can do and how they can stop it; by getting the Stepford Cuckoos to absorb the Phoenix. However, when Emma discovers what the Inner Circle plans to do with the Phoenix, she absorbs the fiery creature into her body, turns into diamond and explodes, releasing the Phoenix into the atmosphere and killing both of them.

Marvel: Ultimate Alliance
In the first game, Dark Phoenix appears at the end of the game. If the player decided to save Nightcrawler instead of Jean Grey in Mephisto's realm, Dark Phoenix will come to Earth and take revenge on the people who refused to save her.

In Marvel: Ultimate Alliance 2, Jean Grey is playable with the Phoenix and Marvel Girl outfits being available for her. When reading Nicky Fury's notes about her, the player can discover that Jean did show up as the Dark Phoenix in the game's back story, and that Fury has got plenty of contigency plans in case she would go red again.

Marvel vs Capcom series
Dark Phoenix appears as a playable character in Marvel vs. Capcom 3: Fate of Two Worlds. If Phoenix's life gets empty and her Hyper Combo Bar is full, she will turn into Dark Phoenix.

Powers and Abilities
Initially, Jean's powers were simply restricted to telekinesis, and even lifting her own weight quickly tired her. With training her telekinesis improved, but it wasn't until after she was released from the stasis chamber she was placed in by the Phoenix Force that her telekinesis really started to become powerful.

Jean's telepathy was suppressed at a young age by Charles Xavier after she connected with her dying friend, Annie Richardson. Later, Xavier released these mental blocks for a more mature Jean.She lost telepathy following her release from the Phoenix egg, only to regain it after battling Psynapse with X-Factor.

While accessing the Phoenix Force, Jean's empathy, telepathy and telekinesis are greatly magnified and heightened to an incredible degree. The Phoenix Force also allows her to travel unaided through the vacuum of space, cross interstellar distances faster than the speed of light, and to manifest flames while using her powers, often in the shape of a fiery raptor. The entity grants her the power to control life and death - she can empty a living being from its life force in order to redistribute it, bath herself in it so she can heal, or even heal/resurrect another being. This power is linked to the Phoenix's ability to come back from the dead.

However, the true extant of the Phoenix Force's power is unknown. While its abilities seem rather simple, it is said that a White Phoenix of the Crown, such as Jean Grey in her past life, is able to bend reality to their will, travel across dimensions, time, space, and even rewrite the past.

Trivia

 * A younger version of the Phoenix in X-Men: Apocalypse was played by Sophie Turner, who was famous for her role of Sansa Stark.
 * The Phoenix Force is often mistaken for Jean Grey, as during The Dark Phoenix Saga events, it took her appearance and personality and lived among the X-Men. It was used as a plot device for the series X-Factor as its authors wanted to bring back the four original X-Men as a new team.