| Name | Character | Episodes |
|---|---|---|
| Roger Smith | Lt. Douglas Roberts | 31 |
| Richard X. Slattery | Captain John Morton | 31 |
| Barry Kelley | 4 | |
| John McCook | 3 | |
| Alan Mowbray | 2 | |
| Henry Gibson | 2 | |
| Tom Brown | 2 | |
| George Takei | 1 | |
| Edd Byrnes | 1 | |
| Wally Cox | 1 | |
| Mimsy Farmer | 1 | |
| Jack Carter | 1 | |
| Barbara Stuart | 1 | |
| Stanley Clements | 1 | |
| Yvonne Craig | 1 | |
| Woodrow Parfrey | 1 | |
| Robert Ito | 1 | |
| Naomi Stevens | 1 | |
| Mamie Van Doren | 1 | |
| Joan Freeman | 1 | |
| James Stacy | 1 | |
| Ernie Anderson | 1 | |
| Joy Harmon | 1 | |
| Barrie Chase | 1 | |
| Patrice Wymore | 1 | |
| Shelley Berman | 1 | |
| Bill Quinn | 1 | |
| Hal Bokar | 1 | |
| Tim Rooney | 1 | |
| Keely Smith | 1 | |
| Lisa Gaye | 1 |