Comic Title: X-Men #40
Publisher: Marvel (Canam Publishers Sales Corp.)
Address: 625 Madison Avenue, New York, NY
Cover Date: January 1968
On Sale Date: November 9, 1967 Copyright Date November 9, 1967
Source: Library of Congress, Periodicals 1968

Frequency: Monthly
Cover Price: $0.12
Page Count: 32
Editor: Stan Lee

Title: "The Mark of the Monster"
Pages: 15

Feature(s):
X-Men

Writer: Roy Thomas
Penciller: Don Heck
Inker: George Tuska
Letterer: Artie Simek

Reprinted In:
X-Men #88 (1974)
Mighty World of Marvel #189 (1976)
Mighty World of Marvel #190 (1976)
Marvel Masterworks Vol. 35:X-Men Vol. 4 HC (2004)
Marvel Masterworks Vol. 35:X-Men Vol. 4 HC [Variant] (2004)
Essential Classic X-Men Vol. 2 TPB (2006)
X-Men:First Class Giant-Size Special #1 (2008)
X-Men Omnibus Vol. 2 HC (2011)
X-Men Omnibus Vol. 2 HC [Variant] (2011)
Marvel Masterworks:The X-Men Vol. 4 TPB (2012)
Marvel Masterworks:The X-Men Vol. 4 TPB [Variant] (2012)
X-Men Epic Collection:Lonely Are the Hunted TPB (2017)

Feature Character(s)

• X-Men (chronology forthcoming)
• Professor X (chronology forthcoming)
• Cyclops (chronology forthcoming)
• Angel (chronology forthcoming)
• Beast (chronology forthcoming)
• Iceman (chronology forthcoming)
• Marvel Girl (chronology forthcoming)