Klamath Osler 「クラマス・オースラー, Kuramasu Ōsurā」 is the third Card Professor who is obsessed with his luck. Jonouchi defeats him. He is named after Klamath Falls, Oregon. "Klamath" is also a pre-release codename for the 300MHz Intel Pentium II chip. His last name, Osler, could be a jumble of the word 'Loser'. He also seems to know Kirk Dixon, mentioning him when he meets with Joey and Tristan. This is futher supported by a picture of himself and Kirk operating remote-controlled toys, based on the monsters that they use.
Klamath uses an Insect Deck that centers around his Antlion.
Pete Coppermine (ピート・コパーマイン, Pīto Kopāmain) is the fifth Card Professor whom Jonouchi defeats. He is named after the Coppermine River in Oregon. The name of that river was used as a codename for the 866MHz Flip Chip Pin Grid Array (FCPGA) Pentium III (P3-850) microprocessor, which was released by Intel.
Mendo Cino (メンド・シーノ, Mendo Shīno) is the seventh Card Professor whom Jonouchi defeats. He calls him a Dollar Store Duelist. "Mendocino" is also a pre-release codename for the 300MHz P6 Intel Pentium II Centrino chip.
Mendo uses a Mantis-themed Insect Deck that centers around using his Labor Pain card to limit his opponents' summoning.
Willa Mette (ウィラ・ミット, Wira Mitto) is the eight Card Professor whom Kaiba defeats. He is later a spectator for Kaiba and Yako's duel. The Willamette is a river in Oregon and a codename for Intel's 1.5 GHz P7 Pentium IV.
Depre Scott (デプレ・スコット, Depure Sukotto) is the eleventh Card Professor and another of Pegasus' adopted sons. He is defeated by Yugi. Prescott was the codename for the 90nm version of Intel's Pentium 4 microprocessor.
Richie Merced (リーチー・マーセーッド, Rīchī Māsēddo) is the twelfth Card Professor and another of Pegasus' adopted sons. He wielded a Black Duel Disk, proof of being the strongest card professor. He defeats Gekkou, and is later defeated by Keith, who takes his Black Disk from him. He seems to care for no one but Pegasus. In a flashback to his past in chapter 27, Richie used to live rough on the streets before Pegasus gave him his deck and taught him to duel, making Richie respect and loyal to the man who saved him from his harsh life. He is last seen with Depre watching Yugi and his friends reunited on the Kaiba Corperation rooftop. Merced was the codename for Itanium, an IA-64 microprocessor developed jointly by Intel and Hewlett-Packard.
Cedar Mill (シｰダｰ・ミｰル, Shīdā Mīru) is the thirteenth Card Professor. Although he's not actually named in the actual manga, dispatched almost offhandedly in a single panel by Yugi's Slifer the Sky Dragon, Cedar is identified in a sketch in the 4th volume of the collected manga. This sketch also identifies Cedar's Deck as a "High-Tech Marionette Deck" 「ハイテックマリオネット」. Cedar Mill is the name of a location in Oregon, as well as the codename for the 65nm version of Intel's Pentium 4 microprocessor.