The Millennium Rod in fan-fics.
Yu-Gi-Oh! X - The Millennium Rod was recharged with the soul of the curator who defiled Pharaoh Seto's tomb. Shadi then tested Seth Kaiba's worth to have it by having Ammeit hold him prisoner and has him try and figure out what the middle tile in a set of nine stone tiles is. With the clue that the tiles are a mirror of Ammeit, Seth figures out that the middle tile is a mouth, and Seth gains the Millennium Rod. Also, Kira's saved from falling. Later, during the second Duelist's Kingdom, Kaiba's connection to Seto allowed the Millennium Rod to give Seth an oral vision of Kaiba calling out to him which emboldend him during his duel with Ghost Kaiba (Gozaburo in disguise). Seth then used the Rod to banish Gozaburo to the Shadow Realm again, and he also used it to force Kemo to release Isis and leave them alone.
The Little Dark Magician Girl II: Return to the Ka World - Seto still posses the Millennium Rod.
Yu-Gi-Oh! Aladdin - Kaiba was after the Rod so he could get rid of Sultan Mutou and take power for himself. After a fluke in the plan, Joey gets ahold of the item and out pops Yami Marik, who introduces himself as the Spirit of the Millennium Rod and promises to grant three wishes, later explaining that he has unlimited powers but is trapped by the Rod. Kaiba manages to steal the Rod and uses its powers to becomes Sultan, then sorcerer, then a Blue-Eyes White Dragon and then is tricked to become a Spirit as well. Joey wishes for Yami Marik's freedom and no longer is he the Spirit of the Millennium Rod.
Yugi Moto and the Duelist's Stone - When Seto was about to enter Hogwarts, the item that chose him was the Millennium Rod.