|Lives:||D Point, near the North Pole|
|Occupation:||Youma under the command of Nephrite|
|First Anime Appearance:||Usagi is Thrilled! Tuxedo Mask's Love Letter|
|First Manga Appearance:||N/A|
|First PGSM Appearance:||N/A|
|English Name:||Leo the Lion|
Regulus was a Youma owned by Nephrite. Nephrite summoned Regulus to lure Sailor Moon and Tuxedo Mask into an elevator that would then fall from the top floor. Once that was accomplished, the Youma disappeared.
This Youma was notable in that it was strong enough to withstand Sailor Moon's Moon Tiara Action attack.
- Regulus was referred to as a Youjuu (妖獣; Bewitching Beast) rather than a Youma in the Sailor Moon Memorial.
- Regulus was unique in that he was one of very few monsters-of-the-day to not be defeated by the Sailor Senshi or their allies.