Creator
Dave Cockrum, Len Wein
  
Arnold Drake, Don heck
  
In Comics
Giant-Size X-Men #1 (May, 1975)
  
The X-Men #49 - Who Dares Defy The Demi-Men?
  
Base
Xavier Institute, Salem Center, Westchester County, New York State
  
Serval Industries, Virginia; formerly X-Factor Investigations Headquarters, Starjammer; Xavier Institute for Higher Learning, Salem Center, Westchester County, New York; Genosha; X-Factor HQ, Washington D.C., Maryland; Mutant Research Center, Muir Island;