| Name | Character | Episodes |
|---|---|---|
| William Shatner | Self - Host | 89 |
| Michio Kaku | Self - Dr. Theoretical Physics Professor | 47 |
| Elon Musk | Self | 2 |
| Jean-Claude Van Damme | Self | 1 |
| Tony Curtis | Self (archive footage) | 1 |
| Amy Winehouse | Self (archive footage) | 1 |
| Michael Jackson | Self (archive footage) | 1 |
| Joseph Stalin | Self (archive footage) | 1 |
| Jules Verne | archivefootage | 1 |
| Jim Morrison | Self (archive footage) | 1 |
| Jimi Hendrix | Self (archive footage) | 1 |
| Kurt Cobain | Self (archive footage) | 1 |
| Janis Joplin | Self (archive footage) | 1 |
| Vladimir Lenin | Self (archive footage) | 1 |
| Harry Houdini | Self (archive footage) | 1 |
| Czar Nicholas II of Russia | Self (archive footage) | 1 |
| Brian Jones | Self (archive footage) | 1 |
| Grand Duchess Anastasia | Self (archive footage) | 1 |
| Jim Jones | Self (archive footage) | 1 |
| Arthur Conan Doyle | Self (archive footage) | 1 |