The Keeper or caretaker of the Shore Leave Planet was a male from an advanced alien race. He was the last individual of this race who resided on the Shore Leave Planet, where he was responsible for overseeing the proper operation of the planet.
In 2267, crew from the USS Enterprise visited this planet, and after a series of unexplained occurrences, they actually met this caretaker. He offered apologies for their confusion, explaining that he had not initially realized the planet's nature was unknown to the visitors. He described the planet as a place his people had constructed so they might play. He then offered the use of the planet for shore leave, as long as appropriate precautions were taken. But the caretaker refused to comment on his people, saying enigmatically that the Federation visitors were not yet ready to understand them – a statement with which Spock concurred. (TOS: "Shore Leave")
In 2269, the Enterprise returned to this world and discovered that the Caretaker had died in the interim. The landing party was directed to his simple grave. His epitaph read: "Last of his race. Ceased to function fifth day of the twelfth moon, year 7009 of this planet." (TAS: "Once Upon a Planet")
The Caretaker was portrayed by Oliver McGowan.
His character was described in the script of "Shore Leave" as "slight, erect, a tremendously dignified robed figure – an aspect of infinite kindness and wisdom." Furthermore, the character was identified as "The Caretaker"/"Caretaker" in the script, the latter of which was how he was credited.
Further references to the character made in "Once Upon a Planet", as described throughout the dialogue, refer to him as "the Keeper of the planet", or more specifically "the Keeper". Indeed, as intended in the script, the top of his headstone was to have read "The Keeper".