Nathalie Sancoeur

Nathalie Sancoeur-Agreste (also known as Nathalie Sancoeur and Mayura) is Gabriel Agreste's personal assistant and also knows of his identity as Hawk Moth, willfully following him out of romantic feelings. She is also the secondary antagonist in the series.

In the two-part season two finale "Heroes Day," she is willingly akumatized by Gabriel into Catalyst, a supervillain who can enhance the powers of others. She then later uses the Peacock Miraculous to transform into Mayura, a peacock-themed supervillain with the power to use corrupted amok feathers to create Sentimonster allies for the villains Gabriel creates as Hawk Moth. While warning of the detrimental side-effects of using the damaged Miraculous, Nathalie expresses her intention to see Gabriel's ambitions realized.[24] In the season 3 finale, after their retreat from Ladybug and Cat Noir, Nathalie gives Gabriel a copy of the Grimoire with all the resolved clues from the book. Her transformation call is "Duusu, Spread My Feathers!"

In season 4, Nathalie is revealed to be in bed-rest after the events of "Miracle Queen", due to her constant use of the formerly broken Peacock Miraculous. However, with knowledge of the identities of Ladybug's allies, she created a sentimonster named Optigami, an origami butterfly-shaped creature with eyes and the ability to camouflage, to spy on the everyday lives of the Miraculous users.