Stan Lee Era (1963-1966)contains X-Men Vol. 1 #1-19
Roy Thomas Era (1966-1968)contains X-Men Vol. 1 #20-43
Various Writers (1968-1969)contains X-Men Vol. 1 #44-66
Chris Claremont and Dave Cockrum (1975-1977)contains Giant-Size X-Men #1 and X-Men Vol. 1 #94-107
Chris Claremont and John Byrne (1977-1980)contains X-Men Vol. 1 #108-#141, X-Men Annual Vol. 1 #3-4, and Uncanny X-Men Vol. 1 #142-143
Chris Claremont and Dave Cockrum II (1981-1982)contains Uncanny X-Men Vol. 1 #144-164 and X-Men Annual Vol. 1 #5-6
Chris Claremont and Paul Smith (1982-1983)contains Marvel Graphic Novel #4-5, New Mutants Vol. 1 #1-12, Uncanny X-Men Vol. 1 #165-175 and Wolverine Vol. 1 #1-4
Chris Claremont and John Romita Jr. (1983-1986)contains Firestar Vol. 1 #1-4, Kitty Pryde and Wolverine #1-6, Longshot Vol. 1 #1-6, Magik #1-4, New Mutants Vol. 1 #13-34, New Mutants Annual #1, New Mutants Special Edition #1, Nightcrawler Vol. 1 #1-4, Uncanny X-Men Vol. 1 #176-209, and X-Men Annual Vol. 1 #7-9
Mutant Massacre (1986)contains Uncanny X-Men Vol. 1 #210-213