X-Men Origins

Emma Frost

Cyclops

Jean Grey

Iceman

Beast

Colossus

Nightcrawler

Gambit

Sabretooth

Wolverine

Deadpool

X-Men Origins

X-Men events from M-Day to Schism (Excluding AvX) 

01//02//03//04//05//06//07//08

House of M - The Day After

New X-Men 20-46

Son of M:

01//02//03//04//05//06

Generation M:

01//02//03//04//05

X-Men: 198

01//02//03//04//05

X-Men: 198 files

X-Men: Blinded by the Light (Messiah Complex prelude)

200//201//202//203//204

01//02//03//04//05//06//

07//08//09//10//11//12//

13

X-Force v3 + Messiah War

See X-23 masterpost  here

01//02//03//04//05//06//07

08//09//10//11//12//13//14

01//02//03//04//05

Regenesis

Astonishing X-Men

Joss Whedon's run on Astonishing X-Men. Also, I think it's a great starting point if you're looking to get into X-Men comics.

01//02//03//04//05//06//07//08//

09//10//11//12//13//14//15//16//

17//18//19//20//21//22//23//24//

Giant Size Astonishing X-Men

New X-Men

New Mutants v2

01//02//03//04//05//06//

07//08//09//10//11//12

New X-Men: Academy X

01//02//03//04//05//06//07//08//09//

10//11//12//13//14//15//16//17//18//19

Hellions

01//02//03//04

New X-Men : Academy X Yearbook Special

01

New X-Men

20//21//22//23//24//25//26//

27//28//29//30//31//32//33//

34//35//36//37//38//39//40//

41//42//43//44//45//46

X-Men: Divided We Stand

01//02