King of the Earth
King Endymion was the name taken by Mamoru Chiba during the reign of Neo-Queen Serenity in the distant future. He did not appear for very long in either the anime or manga, so there is very little known about him. He was always seen wearing a lavender tuxedo and a white mask.
King Endymion's first appearance is at the end of manga Act 18. He is not actually in a physical form but a spiritual entity guarding the Crystal Palace while his real body sleeps. During this time he helps to guide the Sailor Senshi and his past self against the Black Moon Clan. It is then revealed to the Senshi that Mamoru never aged due to the Silver Crystal's power. It is the ghost of King Endymion who instructs Tuxedo Mask in the first use of his attack "Tuxedo La Smoking Bomber."Prince Endymion becomes King at the end of the battle with the Dead Moon Circus when Helios, the priest of his former home, Elysion, hands him his sacred Golden Crystal atop his king's staff. After this, both Tuxedo Mask and Sailor Moon turn into their respective future selves, all of the Sailor Senshi transform into their princess forms. However, after this point, Mamoru is not seen in this form again.
The anime shows King Endymion only in the future as the father of Small Lady and the King of Crystal Tokyo. He also appears as a computerized image when they first meet him. However, he is never shown to fight in battle. Diana makes a comment about the future King and Queen. She says in SuperS that the King and Queen like to fake being sick to be excused from attending important banquets and meetings. In the English dub, he was not referred to as Endymion; only the "King of the Earth" or "The King".
During the second season of the anime, King Endymion sent nightmares to his past self, which caused Mamoru to break up with (and act cold towards) Usagi in order to prevent her from being killed as was depicted in his dreams. This was, however, not the King's intent; he wanted Mamoru and Usagi's bond to be stronger in order to help them survive the onslaught of the Black Moon Clan and Wiseman.