Final Appearance: episode 046
Seiyuu: Tohru Furuya
First appearance: Endymion was an evil incarnation of Mamoru Chiba who was brainwashed to work for the Dark Kingdom. After Mamoru was abducted in episode 035, Queen Metallia and Queen Beryl realized that he was actually Prince Endymion, the prince of the Earth during the Silver Millennium. Under Metallia's orders, Queen Beryl revived Mamoru with dark energy, brainwashing him into working for the Dark Kingdom. His primary mission objectives were to destroy Sailor Moon and obtain the Ginzuishou. In episode 037, Queen Beryl instructed Endymion to work with Kunzite. Both refused, saying that they preferred to do things their own way. Queen Beryl agreed with this arrangement as long as they brought her Sailor Moon's corpse and the Ginzuishou as soon as possible. Endymion began intruding upon Kunzite's schemes, annoying him and often entirely ruining the plan. He would appear during the youma's battle with the Sailor Senshi and instruct the youma not to kill Sailor Moon; he wanted to be the one to collect the Ginzuishou. This led to a fierce rivalry between the two men.
Not quite so evil: On several occasions, Endymion began to remember his past fighting with the Sailor Senshi instead of against them. On these occasions, the black roses he threw would flicker red for a brief instant before turning black again to represent his commitment to the Dark Kingdom. Endymion also maintained at least some code of ethics while he was working for the Dark Kingdom. In episode 039, for instance, he became very angry when the youma Janelyn & Misha harmed an innocent bystander in their search for Sailor Moon. He expressed the same sentiment in episode 040, when a lake monster he awakened went out of control and began harming innocent civilians. After Sailor Moon healed the lake monster and freed her of her ancient jealousy, he was happy to see that it worked out well.
Almost healed: In episode 041, Queen Beryl assigned Endymion the task of capturing the seven former Nijizuishou carriers with the Kurozuishou. The Dark Kingdom hoped that although the former youma had been healed by Sailor Moon, they would be able to use their energy and the power of the Kurozuishou to transform them back into youma. After they were reunited, it was hoped that they would come together to form one extremely powerful youma to destroy the Sailor Senshi. Endymion managed to capture six of the former Nijizuishou carriers before Sailor Mercury destroyed the Kurozuishou, freeing them all. After she destroyed it, she and Sailor Jupiter attacked with Supreme Thunder and Sab„o Spray to stun Endymion long enough for Sailor Moon to use Moon Healing Escalation. His memories came flooding back to him, and he was fully healed. He collapsed, but was quickly transported back to the Dark Kingdom by Queen Beryl. The queen realized that his memories of the past were still not completely erased, so this time, she transfered Queen Metallia's energy directly to Mamoru's body to ensure that he became a faithful Dark Kingdom servant. In episode 042, Endymion was brainwashed once again. This time, he was put under a much more intense brainwashing carried out with the energy of Queen Metallia herself, who said that Endymion's energy shared the same wavelength as hers and that he was worthy of inheriting her energy.
Back to normal: In episode 046, Sailor Moon ventured into the Dark Kingdom's lair to face Queen Beryl. The evil queen revealed Endymion at her feet, kissing her hand. She then instructed the brainwashed man to kill Sailor Moon. He leaped into the air and struck at Sailor Moon with his sword, but she escaped the attack. When she attempted to use "Moon Healing Escalation" on him, it had no effect. He attacked again, this time by throwing a black rose at her, ensnaring her in vines studded with more black roses. Painful bursts of energy passed through her body until she finally collapsed. Queen Beryl instructed him to cut off her head. As he lifted his sword to do so, she attacked him by throwing her tiara at him. Although he was initially stunned, he quickly stood up to try to kill Sailor Moon. In her last, desperate attempt, she held out the open orgel to him and begged him to remember who she was. Endymion ultimately touched the locket, instantly healing him and causing him to regain all of his memories.
Death: After Sailor Moon healed Endymion, Queen Beryl was completely enraged. She created a large black crystal which she threw at the couple. Mamoru quickly reacted by tossing a red rose at the crystal, causing it to shatter mid-air. The shards flew through the air, and Mamoru threw himself at Sailor Moon to protect her. One of the shards fatally pierced his shoulder. The rose he through struck Queen Beryl in the center of her chest, forcing her to temporarily retreat. Mamoru soon died in Sailor Moon's arms as she wept. Fortunately, after Sailor Moon defeated the Dark Kingdom, Mamoru was reincarnated along with everyone else.