| Donald May | Cadet Charles C. Thompson / ... (5 episodes, 1956-1957) |
| Chuck Connors | Maj. Neilson (3 episodes, 1956-1957) |
| Don Eitner | Don Townsend (3 episodes, 1956-1957) |
| Del Erickson | Cadet Harrison / ... (3 episodes, 1956-1957) |
| Richard Jaeckel | (3 episodes, 1956-1957) |
| Steven Terrell | George Nelson (3 episodes, 1956-1957) |
| Larry Thor | Captain Holmes (3 episodes, 1956-1957) |
| Brett Halsey | Stephen Pauley / ... (3 episodes, 1957) |
| Don Garner | Kent Peterson / ... (2 episodes, 1956-1957) |
| Michael Garth | Capt. Rogers / ... (2 episodes, 1956-1957) |
| Race Gentry | Ellsworth Stapleton / ... (2 episodes, 1956-1957) |
| Chester Marshall | Cadet Towne (2 episodes, 1956-1957) |
| Martin Milner | (2 episodes, 1956-1957) |
| Leonard Nimoy | Tom Kennedy (2 episodes, 1956-1957) |
| Larry Pennell | Bob Matson (2 episodes, 1956-1957) |
| Leonard Shoemaker | Cadet Furnas (2 episodes, 1956-1957) |
| Gloria Talbott | Marie / ... (2 episodes, 1956-1957) |
| Jane McArthur | (2 episodes, 1956) |
| Tom Middleton | (2 episodes, 1956) |
| Ted Perritt | (2 episodes, 1956) |
| Valentin de Vargas | Rodriguez (2 episodes, 1957) |
| Donna Martell | Maria Alicia Garcia (2 episodes, 1957) |
| Jan Merlin | Martin Grey (2 episodes, 1957) |
| Dick Sargent | Cadet Daniels / ... (2 episodes, 1957) |
| William Traylor | John Bellson (2 episodes, 1957) |
| Patrick Waltz | Ernie Watts / ... (2 episodes, 1957) |
| Chris Warfield | Dick McKinley (2 episodes, 1957) |
