X-15

David McLean

Matt Powell

Charles Bronson

Lt. Col. Lee Brandon

Mary Tyler Moore

Pamela Stewart

Stanley Livingston

Mike Brandon

Ralph Taeger

Maj. Ernest Wilde

Brad Dexter

Maj. Anthony Rinaldi

Kenneth Tobey

Col. Craig Brewster

James Gregory

Tom Deparma

Patricia Owens

Margaret Brandon

James Stewart

Himself / Narrator (voice)

Lisabeth Hush

Diane Wilde

Lauren Gilbert

Col. Jessup

Frank Watkins

Security Policeman

Dick Wilson

Flight Engineer