Frost

Frost is the Quirk used by Rei Todoroki and her children, Dabi, Fuyumi, and Natsuo.

Description
Frost gives the user the capability of manipulating and producing ice around their body.

Rei's possession of this Quirk was what directly resulted in her Quirk Marriage with Enji Todoroki to create a child that possessed a perfect fusion of it and his Hellflame Quirk. The second and third children, Fuyumi and Natsuo, inherited the Frost Quirk, while the eldest, Toya, inherited a stronger version of Hellflame, but Frost's resistance to ice and weakness to fire. The youngest son, Shoto eventually developed the combination Quirk that Enji so desired, Half-Cold Half-Hot, containing the strength of both Quirks as well as the way to alleviate their respective weaknesses.

Usage
Rei is first seen using this Quirk to attempt to heal Shoto after she instinctively throws boiling water at him. Fuyumi and Natsuo have both not yet demonstrated their capabilities with the Quirk.

During the Final War, while on the verge of death, Dabi manifested his mother's Quirk, using it to empower his Phosphor Ultimate Move in combination with his given Quirk, Blueflame.

Trivia

 * Frost's name was never given in the manga. It is only named as such in the anime.
 * Frost is said to give the user a sensitivity to warmer weather, as well as liking for cooler one.