Minor characters in High School DxD.
Kiyome Abe's Monsters
Mr. Smith
Mr. Smith (スミス氏, Sumisu-shi) is a Dullahan, a set of living animate armor with a detachable helmet for a head who is also under Kiyome Abe. He appeared in "The Oppai of Tennis" Short Story where its head was hospitalised with a hernia, during which Kiyome Abe, a beast tamer, looked after his horse and body which she gave the job as the Tennis Club mascot, nicknamed "No-Head Honda-kun" (ノーヘッド本田 Nōheddo Honda), who was very popular among the members.
He is able to give immense strength to its wearer but the person wearing it cannot take it off easily due to a curse. During the tennis match between Rias and Kiyome, Honda wore itself around Issei to help him win. The armor gets hot often so it was able to help protect Issei from Christie's freezing breath during the tennis match with Abe. Normally Honda wouldn't be allowed near the tennis team, but Rias and Sona were okay with it since he was doing it as a mascot.
Harpy
An unnamed Harpy girl who serves under Kiyome Abe who taught her how to play Tennis at her club. She appears to be a cute young girl with short feather-like hair and winged ears. She is mostly naked, wearing nothing but a pair of panties while feathers cover her large chest. Her most notable features is her bird-like appearance, having bird wings for arms, feathered tail and avian legs with talons.
She first appeared in "Issei SOS" Short Story, where she played on Kiyome's team against the Occult Research Club, where she was matched up against Akeno for the first round and lost very easily.
Lamia
An unnamed Lamia girl who serves under Kiyome Abe who taught her how to play Tennis at her club. Her upper body appears mostly human with a curvy figure while her lower half is a large snake tail. She has long dark hair.
She first appeared in "Issei SOS" Short Story, where she played on Kiyome's team against the Occult Research Club, where she was matched up against Xenovia for the second round, some thought that her not having legs would be a disadvantage, but in fact helped her stretch across the court quickly without moving, gaining herself a win.
Estleena
Estleena (エストリーナ, Esutorīna) is Mermaid who serves under Kiyome Abe. Estleena is a breed of mermaids with the upper body of a Tuna fish with muscular legs.
Estleena first appeared in "Issei SOS" Short Story, where she was partnered with Issei against Kiyome Abe's father and a Shark variant Mermaid for the second match. Issei was horribly disappointed upon seeing that she did not resemble the mermaids from common myth. However both died due to staying out of the water for too long, Issei won due to Estleena dying last, later on everyone ate their fins for dinner.
Sky Takahashi
Sky Takahashi 高橋 輝空, Takahashi Sukai is a Birdman who serves as Kiyome Abe's personal bodyguard. Sky appears to be a young man, with a cockscomb on his head, a beak for his mouth and bird wings for his arms. He wears a sleeveless jacket and shirt with a tie. Sky appears to love the feeling of wind blowing on his skin. He has a tendency to forget recent events after walking three steps.
Sky first appeared in "Issei SOS" Short Story, warning Kiyome in advanced that her father will be arriving home soon. He was later assigned to be Issei's partner for the third and final match against Kiyome's father between sky monsters within the mountains. Kiyome's rides rides on a large bird while Issei piggybacked on Sky, it is then to Issei's surprise that while Sky can run fast his breed is unable to fly. Issei's friends devised a plan for him, Sky waved his arms to gain the gain birds attention, Gasper used his power to freeze the large bird which then landed on Sky.
Typhon's Offsprings
Orthrus
Orthrus (オルトロス, Orutorosu) is the offspring of the Typhon and Echidna. He is a two-headed dog who guarded Geryon's cattle and was killed by the original Heracles. He is also the brother of Cerberus, who was also a multi-headed guard dog.
Orthrus later joined it's progenitor; Typhon's Azazel Cup team; Team Leisure of the Kings as a Pawn.
Sphinx
Sphinx (スフィンクス, Sufinkusu) is the daughter of Typhon and Echidna. Sphinx has the head of a woman, the haunches of a lion, and the wings of a bird.
The Sphinx later joined it's progenitor; Typhon's Azazel Cup team; Team Leisure of the Kings as a Pawn.
Hydra
Hydra (ヒュドラ, Hyudora) is the offspring of Typhon and Echidna. It has poisonous breath and blood so virulent that even its scent was deadly. The Hydra possesses a unknown amount of heads, and the ability to regenerate them as for every head chopped off, the Hydra would regrow two heads. Defeating a Hydra was one of the original Heracles' Twelve Labors.
In Volume 8, a Hydra was listed as a potential familiar for Issei. The Hydra was described as a gigantic serpent with many heads as it has sharp eyes, sharp fangs and there is a poisonous mark of a skeleton. According to Zatouji, the Hydra is the worst immortal creature in the World which even kills its master, possessing a deadly poison that no Devil can endure.
In Volume 13, during the Three Factions Sports Day, a Hydra was positioned as a obstacle in the obstacle course race.
A Hydra later joined it's progenitor; Typhon's Azazel Cup team; Team Leisure of the Kings as a Pawn.
Other Monsters
Bob
Bob (ボブ, Bobu) is a Cerberus owned by Iolava Amon that first appeared in the sort story "Having a Mad Tea Party!". Bob was created and modified under Iolava's request from being inspired by Issei's Dress Break spell, in which it could tear off a person's clothes with just a stare. Iolava demonstrated this when he unleashed Bob from his cage and tore off a woman's dress and planned to strip every woman present, Issei was initially impressed by this but was disgusted when it also tore the clothes off men as well. Issei fought the Cerberus in his Balance Breaker and put Bob back in his cage.
Medusa
Medusa (メデューサ, Mede~yūsa) was a Gorgon having snake heads in place of hair with the ability to petrify anyone into stone upon eye contact. In Greek mythology, she was slayed and beheaded by the Hero Perseus. In Volume 9, one of her eyes was implanted into Cao Cao in place of the one he lost, thus granting him her ability. In Volume 12, his eye was damaged when Issei used Samael's curse on it.
Falak
Falak (ファラック, Farakku) a giant snake ruler whose stomach is rumored to be connected with Hell. Usually she takes the appearance of a human woman. She is Ajuka Beelzebub's Queen.
