Characters played by Rod Serling
Narrator
Characters played by Roy E. Cameron
Self - Microbiologist (as Dr. Roy Cameron)
Characters played by M.C. Chang
Self (as Dr. M.C. Chang)
Characters played by Patrick Flanagan
Self
Characters played by Art Ford
Self
Characters played by Tim Gill
Self - Yerkes Primate Researcher
Characters played by E.S.E. Hafez
Self (as Dr. E.S.E. Hafez)
Characters played by Duncan A. Lunan
Self
Characters played by Thelma Moss
Self (as Dr. Thelmas Moss)
Characters played by Leslie Orgel
Self (as Dr. Leslie Orgel)
Characters played by Ernst von Glasersfeld
Self