Thelonious Viper

Professor Viper(プロフェッサー・コブラ Purofessā Kobura) is a professor hailing from West Academy (West School). In the Japanese version, Viper is voiced by Masaya Takatsuka.

Viper enters Duel Academy in the third year. In a desperate attempt to aid Yubel, who promised raise his son from the dead, Proff. Viper pits students against one another in Dis-Duels. He is tricked into believing that Rick never died upon losing to Jaden in a Duel, and seemingly falls to his death after stepping off the dueling platform.

Deck
Viper plays a Venom deck, themed on the distribution of Venom Counters through his Reptile-type monsters (such as Venom Snake and Venom Boa) to an opponent's monsters as means of weakening and ultimately destroying them. Several of his monsters are based on the nāga, a serpent-like race in Hindu and Buddhist mythology. One of these creatures, Viper's signature card "Venominaga, the Deity of Venomous Serpents", is able to circulate poison in the opponent's body upon causing damage, declaring an automatic victory for its owner within three turns.