I have an extensive comics collection from my chilhood-20's and I refered to the Marvel X-Men trading cards including the Xavier's Files and Cerbro Scan sets to answer a few questions for people who enjoyed the movie and might enjoy some comics backround on some of the notable characters :beer:
1. Lady Deathstrike has no mutant powers in the comics, she has enhanced strength and reflexes, and adamantium finger-claws that are
mechanical in origin hence no infusion like Wolvie which required a accelerated healing factor. She is also sheathed in alien body armor. Wolvie didn't kill her pop, but she thinks he did and underwent experiments conducted by "the evil Spiral" that "mangled her flesh and made her a cyborg killing machine" (from Xavier's Files and Cerebro Scan *Cerebro set is awesome because it has a scale for complete power rating including Energy Projection, Mental powers, Strength, Fighting ability, and Intelligence*) Lady DeathStrike is a 6 of possible 7 in fighting ability.
2. The info provided by others on the Dark Phoenix is accurate and Jean is put in suspended animation by the Phoenix when it supplanted her. A notable point is that Phoenix is Jean and Scott's daughter and one of the many refugees from the future. Her name is Rachel Summers and her energy projection and mental powers are off the scale! She is a member of Excaliber and a side note is that she makes use of her powers to hide horrible facial tattoos that scar her face.
3. I'm surprised that people still question Jackman as wolvie as I thought everyone got over it with the first movie, I was wrong. BTW Logan has a perfect 7 for fighting ability.
4. Siryn A.K.A. Theresa Rourke can fly in the comics, she is a member of X-Force, and her uncle is a super villian named Black Tom Cassidy.
5. Sabretooth may not have appeared but he's not dead, he has a healing factor very much like Logan's which makes him immune to most any drug or poison. He and Logan were part of the weaponX project, he also has the max 7 for fighting ability, and he may have just fell out of favor with Magneto because he's not the sharpest tool in the shed so to speak and could potentially turn on him at any moment, plus he makes his living as an assassin/hired gun so he may be off makin' some bank. I've read enough in the past to know they speculate he and Logan are related and someone here mentioned he's Logan's dad, I don't know if that's the relationship but there is definitely one, maybe Creed is his older bro? It would explain why they are almost identical in beastial fury, healing powers, fighting ability, intense hatred of each other (sibiling rivalry) and why Creed calls him runt and it gets Logan so bent.
6. Colossus turns into organic steel, has a strength rating of 6 and despises violence of any kind. The classic gentle giant, and he only fights hoping to eliminate evil that he may fight no more, naive but noble, hence why they say he has the soul of a poet.
7.NightCrawler was abandoned at birth a raised by a sorceress named Margali Szardoz. He has a fighting level of 5, extreme agility and athleticism, and ended up with Excaliber.
The other characters are more popular and probably need no backround provided for even most non comics fans especially since the films expanded on them more. Anyways, I thought the movie was great, I have no nitpicking to do, I felt they treated the property amazingly well and made it everything you hope a comic to film will be

I do need to see it again though because xeno2060 drove and I slammed vodka shots before leaving, then more drinks@TGIF's bar down the street from the theaters so I missed some stuff
