Crimson Rubeus (紅のルベウス Kurenai no Rubeusu) is a red-haired human and the first member of the Black Moon Clan to appear in the 20th century. He is charged with finding a person codenamed "Rabbit", who had fled into the Tokyo of the past. Besides following the orders of Prince Demand and Wiseman, he leads his own set of minions, the Ayakashi Sisters.
He captures Sailors Mars, Mercury, and Jupiter but is unable to capture Sailor Venus. He is loyal to Prince Demand, appearing with him to taunt the captured Sailor Moon. Overhearing Neo Queen Serenity speaking through Sailor Moon, Rubeus realizes that there is more to Wiseman than what he sees and confronts him. He is mercilessly killed by Wiseman using Black Lady's powers when he attempted to warn Demand and Saphir about him. His warning didn't go unheard as Demand later discovered the truth of Wiseman's treachery.
In Sailor Moon R, Rubeus is the love interest to Kōan arrives and arrives in the present looking for Chibiusa. Despite the Ayakashi Sisters' love for Rubeus, he does not reciprocate their feelings and uses them as pawns. He attempts to kill the Ayakashi Sisters, but when they reform, Esmeraude warns Rubeus that Prince Demand is getting impatient with Rubeus' failures and plans to release him. Afterwards, Rubeus captures the Sailor Soldiers and has Sailor Moon bring the Silver Crystal in exchange for her friends. Sailor Moon comes to rescue them, and in the ensuing battle, Chibiusa destroys the crystal controlling his ship, and the Sailor Soldiers are freed and they return to Earth. Esmeraude reminds Rubeus that he has failed too many times and that she is assuming command, before leaving Rubeus to die in the explosion.
Rubeus appears as a boss in the "Sailor Moon: Another Story" video game. He is encountered in the past outside of the Ark near the Temple of Venus in Rias.
In the anime, Crimson Rubeus was voiced by Wataru Takagi and by Hiroki Takahashi in Crystal. In the DIC English adaptation, he was voiced by Robert Tinkler. In the Viz Media English adaptation, he is voiced by Steve Cannon. In themusicals, Rubeus was portrayed by Hiroyuki Ichikawa and Riona Tatemichi.