Rias Gremory (?????????, Riasu Guremor?) is a fictional character who appears in the light novel, anime, and manga series High School DxD authored by Ichiei Ishibumi. Rias is the main love interest of the protagonist, Issei Hyodo. Rias is a high school student at Kuoh Academy, which, unbeknownst to most students, contains angels, devils, and fallen angels as part of its student population. High School DxD is set in a world where there is constant battle between these three main factions (angels, devils, fallen angels), though the war has died down as of late, and many famous angels and devils have already ceased to exist.
A devil of the Gremory clan, one of the highest-ranking devil families, Rias initially saves Issei after he was attacked by a fallen angel, Raynare. Issei wakes up the next morning, thinking that the events that occurred were all just a dream, but then notices Rias naked in his room. Rias reveals to Issei her true identity as a devil and says that as a result of his death at the hands of Raynare, she has reincarnated him as a devil, becoming his new master in the process. Rias is the head of Kuoh Academy's Occult Research school club, where Issei, Rias, and the club members interact with various groups and organizations, some of which are run by devils who compete against them in sanctioned combat matches called Rating Games, where the characters have been assigned positions akin to chess pieces.
Rias has received mostly positive critical reception. Reviewers have complimented the character's design, personality, and relationship with Issei, as well as her physical attractiveness. Her backstory has also been the recipient of some praise, though some reviewers have critiqued her character as uninteresting. Rias has achieved popularity in anime and manga fandom, and has appeared on numerous lists and surveys of the most popular anime and manga characters. Numerous High School DxD merchandise featuring Rias have also been released, including figurines and video games. The character is also a popular choice amongst cosplayers.