| Description | Living Machine |
| Size | Large |
| Skin Pigment | None |
| Hair | None |
| Distinguishing Features | Resembles a large rock outcrop with a window. |
| Series | TOS: "The City on the Edge of Forever", TAS: "Yesteryear" |
| Planet of Origin | UFC 465537 (aka: "Planet time") |
| Quadrant | Alpha (assumed) |
| Background | The Guardian of Forever is a machine-creature that allow to travel in the time, met on a planet called "Time Planet". This world is the only planet of a giant red in exhaustion. The Guardian is more than ten million years old. Once, the homeland of the civilization has been more advance that has populated the known space. It is not known much of this civilization, with the exception of any ruins in the northern hemisphere and an entity that calls itself neither "creature" neither "machine" and he tells to be called "Guardian of Forever". The material and the principles on which the Guardian of Forever bases itself are completely unknown. His function seems to be that of show the past of any planet and of allow a journey in the time. |
| Editors Notes | The planet has been set under quarantine and the Federation Counsel has voted the unanimity the General Prohibition P-119 that it establishes that no person or vessel under any circumstance could approach to the UFC system 465537. |