Despite only being seen in flashbacks, he is a posthumous antagonist of the Battle City arc, and the overarching antagonist of the Tournament Finals arc, and the second season of the anime Yu-G-Oh! Duel Monsters, as his actions were responsible for the creation of Yami Marik, and for leading his son's main personality down a darker path to begin with.
He was voiced by Motomu Anzaki in Japanese and Richard Will in English.
Mr. Ishtar was the tombkeeper of the Pharaoh who guarded the Millennium Rod and Millennium Necklace. He also had a wife who appeared to be infertile, which angered him because he needed a male heir to continue the tombkeeper duties after him. One day, his wife found a baby boy left in the ruins by their underground home, though he apparently allowed her to keep the child and raise him, he personally never saw Rishid as part of the family or cared for him the slightest. When Rishid was still young he and his wife talked about needing an heir, though Mr. Ishtar was reluctant to name Rishid his heir as tradition required a blood child, though he reluctantly agreed to do so if they did not have a son by his twelfth birthday. Some time later, his wife bore a daughter she named Ishizu, though disappointed that it wasn't a son, Mr. Ishtar was happy to see that he and his wife could bear children and proclaimed that all they needed now was a boy.
Years later, Mrs. Ishtar sadly died giving birth to Marik. Her husband showed no sadness about this because he now had an heir. With a true heir and his wife dead, he then reduced Rishid to a slave and would threaten him with death or injury for failures. When Marik was bitten by a rattlesnake while under Rishid's watch he berated the boy for his lack of caution and ordered him to stay by Marik's bedside until he was better, while threatening to kill him for future incidents. When Marik turned twelve, he was to be prepared to take the duties as tombkeeper, which required him to have the Pharaoh's story carved into his back. Rishid approached Mr. Ishtar and told him how terrified Marik was and begged to take his place as tombkeeper. However Mr. Ishtar was unmoved and stated that Marik will go through with the ritual and threatened to cut off Rishid's tongue if he spoke another word on it. He would later go on to sadistically carve up his son's back as an ancient ritual, and the anger and hate Marik felt towards his father would eventually form Yami Marik. Later on, Rishid had his face carved to resemble the ritual as well, both to ease Marik s anger and show his dedication to the family, but Mr. Ishtar was once again unmoved by Rishnids dedication and ordered him to cover his face. When Marik and his sister Ishizu snuck out (which was strictly forbidden to do) and his father found out, he was about to banish Rishid after torturing him with a heated blade (or whip) (or weakening him with the Millennium Rod in the anime), when Yami Marik took over Marik's body and claimed the Millennium Rod for himself. Mr. Ishtar was horrified that his abusive treatment created this evil entity in his son . Yami Marik stabbed Marik's father to death (while in the 4Kids version, he sent his father to the Shadow Realm though there is little difference between death and being banished to the Shadow Realm).
- Due to the graphic nature of Mr. Ishtar's crimes, he was severely toned down in the 4kids dub. Though still cruel and uncaring, his abuse of Rishid (named Odion) was toned down somewhat, removing his threats of mutilation and death. Also while in the original sources he tortures him to a presumed death for letting Marik and his sister go, in the dub he instead weakens him with the Millennium Rod and planned to banish him. Though he's still evil in all other respects and his lack of care for others remains the same. Also in the dub he tattoos the ritual onto Marik's back rather than carved, though it still hurts greatly.
- Mr. Ishtar is responsible for the creation of Yami Marik because had he not tortured his son, Yami Marik would have never been created and he might still be alive. This makes him the Greater Scope Villain of the Battle City arc.
- Mr. Ishtar and Marik look very similar (except for the beard, and Mr. Ishtar's facial features show that he's older).
- He may be a reincarnation of Aknadin due to their similar appearances. Though if this was true it would be very ironic as Aknadin had betrayed the Pharaoh and attempted to place his own son on the throne while Mr. Ishtar was fanatically loyal to the Pharaoh to the point that his family meant very little to him.