- Fred MacMurray
- Wilson Daniels
- Jean Hagen
- Freeda Daniels
- Tommy Kirk
- Wilby Daniels
- Annette Funicello
- Allison D'Allessio
- Tim Considine
- Buzz Miller
- Kevin Corcoran
- Moochie (Montgomery) Daniels
- Cecil Kellaway
- Professor Plumcutt
- Alexander Scourby
- Dr. Mikhail Andrassy
- Roberta Shore
- Franceska Andrassy
- James Westerfield
- Officer Hanson
- Strother Martin
- Thurm
- Forrest Lewis
- Officer Kelly
- Ned Wever
- FBI Chief E.P. Hackett
- Gordon Jones
- Captain Scanlon, Police Chief
- Jacques Aubuchon
- Stefano
- Jack Albertson
- Reporter
- Jim Bannon
- Betz, FBI Stenographer
- Larry J. Blake
- Police Officer Ed Mercer
- Charles Cane
- Mercer's Patrol Carl Partner
- Ken Clark
- FBI Agent
- George Ford
- Party Guest
- Paul Frees
- Narrator / J.W. Galvin, Psychiatrist (uncredited)
- John Hart
- Police Broadcaster
- Susie Hawkins
- Little girl with boy at party
- Hans Moebus
- Party Guest
- Gregg Palmer
- FBI Agent
- Mark Rodney
- Kid at Dance
- Shaggy
- Chiffon
- Mack Williams
- FBI Agent
