Robert Vaughn as Napoleon Solo

David McCallum as Illya Kuryakin

Barry Sullivan as Dr. Robert Kingsley

Eleanor Parker as Margitta Kingsley

Leslie Nielsen as General Maximilian Harmon

Leo G. Carroll as Alexander Waverly

Tony Bill as Steven Garrow

Peter Mark Richman as Mr. Webb

Albert Paulsen as Dr. Kurt Erikson

Inger Stratton as Anna Erikson

Hugh Marlowe as Grant

Amy Thomson as Miss Carla

Dan O'Herlihy as Prof. David Garrow

Ruth Warrick as Alice Garrow

David Hurst as Dr. Jan Vanovech

Barbara Moore as Lisa Rogers

Arthur Hanson as Paul Mackie

Richard Bull as Capt. Gelser

Edgar Stehli as Veeth

Annella Bassett as Dr. Naomi Fisher

Logan Ramsey as Ship's Captain

Guy Lee as Cab Driver

Ray Weaver as Reporter

Michael Masters as Reporter