The Dark Phoenix Saga - Chris Claremont (writer) & John Bryne (penciler)

Jean Grey could have lived to become a god. But it was more important to her that she die … a human
X-Men remains one of the most enduring and loved comic book franchises of all time, because in Stan Lee’s words “never in the history of comicdom have there been stories more filled human interest, believable characterization, far-out fantasy combined with stark, shattering realism“. And no story arc epitomizes these words better than the Dark Phoenix Saga, the tale of Jean Grey realizing her ultimate potential and horror of being the Phoenix and choosing to sacrifice herself to save the universe.
Since the time it was first published, Jean Grey has been resurrected many times over as her moniker Phoenix suggests and many others have taken the mantle but nothing matches the sheer shock of seeing Jean Grey, literally the girl next door, turn into the devourer of worlds. Even when she destroys a world and the billions of lives inhabiting it, genocide of a scale that Hitler would flinch at, the reader is still forgiving her for she is not Jean Grey but the Dark Phoenix. But she realizes, much before the reader does, that the Dark Phoenix and Jean Grey are one and the same. It is not possible to let one live and other die. For the safety of the worlds she has to die.
But again in Stan Lee’s words DPS is not only about Jean’s sacrifice; it is also about Cyclops‘ sorrow, Kitty Pryde’s discovery of her powers, the deviousness of Mastermind as Jason Wyngarde and diabolical conniving of the Hellfire club. It is first and foremost a very very well told story; much better than one will find in award winning movies or best selling novels.
Lastly, though the X-Men movies are amongst the reasonably well made comic book movies, X-Men-The Last Stand, which incorporates elements from this story arc, does scarce justice to the Dark Phoenix Saga. It neither brings out the frailty of Jean’s humanity in face of Phoenix’s divinity nor does it show her mental strength in choosing and accepting her fate.