Aknadin

Aknadin, known as Akhenaden in the manga and Japanese version, is the father of High Priest Seto and younger twin brother to the former Pharaoh Aknamkanon, thus making him the uncle to the current Pharaoh Atem. He was also the first owner of the Millennium Eye.

Creation of the Millennium Items
Akhenaden was the advisor and brother of Pharaoh Aknamkanon. While he loved his brother dearly, he was secretly resentful of his brother for being Pharaoh while he was relatively unimportant. When Egypt was under attack, Aknadin pushed his brother to fight back and protect his people, but Aknamkanon refused on the grounds he wanted peace. Eventually the invading armies grew too close to the palace to be repelled, and Akhenaden suggested using a spell from the Millennium Spellbook ("Millennium Tome" in the manga) to create the Millennium Items. Faced with the undeniable fact his kingdom may be destroyed, Aknamkanon agreed. It is later revealed in the manga that Zorc Necrophades had lured Akhenaden (most likely with promises of his legacy obtaining the throne from his brother) to translate the Millennium Tome (hence the Shadow Alchemy and the events of Kul Elna) in order for him to be brought back into the world.

Akhenaden abandoned his son Seto and his wife for fear his actions would later cause criminals to target them, as well as to shield them from prejudice. Akhenaden led a group of soldiers to the village of Kul Elna, where he ordered the thieves there killed, and their blood collected for the ritual to create the items (in the English anime, the souls of the thieves are collected, although it is indirectly implied they are still killed). The only survivor of this slaughter was Bakura. The slaughter was so horrific that Akhenaden never told his brother of it, and had all the soldiers he had taken brainwashed so as to forget the incident.

Akhenaden succeeded in crafting the Millennium Items, but a chasm opened in the chamber where the ritual has taken place. Zorc Necrophades rose from the chasm and ensnared Akhenaden, presumably to kill him. Akhenaden gouged out his eye and placed the Millennium Eye into the socket, using its magic to protect himself and repel Zorc (in the manga, he just simply puts on the Eye wishing his son, Seto, to be pharaoh). On the journey back to the palace, all the soldiers but Akhenaden fell, and only he survived. Upon the invading army's attack, Akhenaden, his brother and five other priests used the Millennium Items to hold them at bay and defeat them.

Akhenaden would later remain a member of the Sacred Court after his brother sacrificed himself and his son Atem took the throne. Akhenaden also witnessed his son Seto's rise to power as the High Priest and holder of the Millennium Rod. Akhenaden was amazed his son had made his way from peasant to priest despite him abandoning him, and spent all his spare time training Seto, although he never told him they were related. Both Seto and Atem were unaware that they were cousins, although if Atem knew Akhenaden was his uncle or not is not addressed.

Dawn of the Duel events
In the Dawn of the Duel story arc, when Thief King Bakura attacked the Royal Palace and accused Atem's father of slaughtering his village, the Sacred Court denied such claims, but Akhenaden was horrified to realize Bakura must have survived the destruction, and as a result of the rage and evil that surely had taken root in him, the power of his Ka "Diabound" would be nearly limitless. Using the power of his Millennium Ring to get past the guards, Bakura would later attack Akhenaden at the palace itself, and promise him Akhenaden's dark side would be brought out. Exactly what he did to Akhenaden is not known, although it affected his mind, and he became convinced his son should be Pharaoh. In an act that would ultimately lead to Atem's defeat (but not death), he attacked the stone tablet that housed Slifer the Sky Dragon, weakening it for Bakura to defeat it and cast Atem into a chasm.

Akhenaden then had several prisoners, including the young girl Kisara, taken to a secret underground arena where he made them battle each other using their Ka. When Seto found him, Akhenaden explained he (Seto) would be the next Pharaoh, and he was simply doing his duty to him by creating an army for him: by having the prisoners fight, their evil souls grew stronger and their ka more deadly. When Akhenaden ordered Kisara to battle, Seto stepped in to save her at the risk of his own life, refusing to let Akhenaden kill her or to extract her Ka, the White Dragon.

Akhenaden accompanied the attack on Kul Elna, where he and the priest Shada found the tablet for Bakura's Ka Diabound. When Shada attempts to tell the other priests, Akhenaden knocks him unconscious and takes his Millennium Key. During this time, Bakura had been defeated by Atem, Mahado (Mahad in the English anime) and Mana. Overseeing the events, Yami Bakura used a talisman to freeze time, while Akhenaden collected the remaining Millennium Items from the incapacitated priests and placed them in the Millennium Stone to call Zorc.

Transformation into "Shadow Magus"
Zorc endowed Akhenaden with the power of the shadows and transformed him into the Shadow Magus (High Priest of Darkness in the manga).

Akhenaden then proceeded to tell Seto of his royal lineage, encouraging him to join him and rule the world with him and Zorc. Seto refused, and Akhenaden attacked, only to be repelled when Hassan stepped in to protect them. During this time Yami Bakura used the power of the Millennium Items to revive Bakura and Diabound (in the anime, he used some of the lifeforce of Seto Kaiba, who recently entered the Memory World, to revive Thief King Bakura), who distracted the priests while Akhenaden drew Seto into a portal to appear at the palace, where he had also teleported Kisara. Seto protected Kisara once again, and Kisara responded in kind by calling forth the White Dragon to battle Akhenaden.

Akhenaden sealed the White Dragon in stone before killing Kisara herself (Kisara's spirit is sealed with the White Dragon in the English dub). Seto responded by summoning the White Dragon himself to strike down Akhenaden before stabbing him and killing him. Akhenaden sent his spirit into Seto, and controlled him to attack Atem who had just arrived. Atem was overpowered, but the spirit of Kisara in the form of the White Dragon entered Seto's mind, where she destroyed Akhenaden for good. In the English Dub, Aknadin is sent to the Shadow Realm. At the end of the ceremonial battle, Akhenaden is seen as one of the souls waiting for Atem in the after life.

In the Yu-Gi-Oh! GX manga, Akhenaden makes a possible appearance as a figure in the past of Tragoedia and appears (along with Seto and Karim) to have been responsible for sealing him.