Milady de Winter acts as a primary antagonist in the anime adaptation of *The Three Musketeers*. She spies for Cardinal Richelieu, actively working to undermine Queen Anne of Austria. Her schemes involve orchestrating the diamond necklace scandal to discredit the queen, leveraging her beauty and cunning to manipulate others. She possesses a distinctive trait of animal control, utilizing a magical whistle to command creatures for espionage or sabotage. Her pet monkey, Pepe, serves as both companion and accomplice, assisting in tasks like surveillance and delivering an antidote during her faked death by poison.

This adaptation provides her with a sympathetic backstory: imprisoned in her youth for her Protestant faith, she was later recast by Richelieu as "Charlotte," a false noblewoman trained to infiltrate the royal court. Her appearance includes green hair and a frequently worn domino mask, though the mask proves ineffective at concealing her identity. She demonstrates proficiency with daggers and employs disguises to evade detection.

Character development reveals moments of vulnerability. After exposure and defeat, she faces isolation and prays for divine forgiveness before her demise. A significant deviation from the source material is the absence of her marriage to Athos; her conflicts center instead on political machinations and personal survival. Her fate concludes with a solitary death. Throughout the series, she participates in extended plotlines, such as the "Iron Mask" arc where she allies with the titular villain, though her loyalty remains self-serving and culminates in betrayals when cornered.