List of X-15 test pilots as given in Wikipedia
(Not sure how well this will format, but here goes):
Pilot/ Organization/ Total Flights
Michael J. Adams† U.S. Air Force 7
Neil Armstrong NASA 7
Scott Crossfield North American Aviation 14
William H. Dana NASA 16
Joe H. Engle U.S. Air Force 16
William “Pete” Knight U.S. Air Force 16
John B. McKay NASA 29
Forrest S. Petersen U.S. Navy 5
Robert Rushworth U.S. Air Force 34
Milt Thompson NASA 14
Joseph A. Walker NASA 25
Robert M. White** U.S. Air Force 16
I remember the X-15 program from when I was a little boy, the coverage of Scott Crossfield’s flights in particular.
And the citation by Adams name is a footnote that he died in an X-15 crash, the only fatality noted.
(Sorry about the lousy formatting - I need to go to html school)