Thelonious Viper with "Venom Boa", "Venom Serpent" and "Venom Snake".
"Venom" (ヴェノム Venomu) is an archetype consisting of Reptile-Type monsters used by Thelonious Viper in the Yu-Gi-Oh! GX anime and introduced in Tactical Evolution. They focus on the distribution of Venom Counters via "Venom Swamp", while their strongest monsters (which are not technically a part of the archetype, but related to it) gain ATK for each Reptile-Type monster in the Graveyard. "Vennominaga the Deity of Poisonous Snakes" gives an alternate win condition via its Hyper Venom Counters. All monsters of this archetype are EARTH-Attribute (except "Venom Serpent", "Starving Venom Fusion Dragon", and "Greedy Venom Fusion Dragon", all of which are DARK instead).
The dimension dragon and his upgraded counterpart, "Starving Venom Fusion Dragon" and "Greedy Venom Fusion Dragon", are seen as somewhat of outsiders to this archetypes, as only 1 Main Deck Venom Monster is DARK.
The Deck focuses on lowering the opponent's monsters' ATK with "Venom Swamp" and Summoning "Vennominon the King of Poisonous Snakes" or "Vennominaga the Deity of Poisonous Snakes". Since the ATK of both cards are dependent on the number of Reptiles in your Graveyard, cards like "Foolish Burial" and "Snake Rain" are important in this Deck. Also, there are not many "Venom" monsters, so a hybrid with other Decks is inevitable.
"Venom Swamp" is able to quickly weaken and eventually destroy any non-"Venom" monster. Also, even if "Venom Swamp" is not on the field, "Venom Burn" can inflict serious damage to a player's Life Points"
- The Deck relies on "Venom Swamp" for Venom Counters to have any effect on monsters, so if "Venom Swamp" is destroyed, Venom Counters are almost useless. This bad situation can be avoided by "Spell Reclamation".
- Summoning "Vennominaga the Deity of Poisonous Snakes" is difficult since you need to Summon it with "Rise of the Snake Deity", meaning that "Seven Tools of the Bandit" or "Wiretap" can halt the Summon.
- The main weakness of the "Venom" Deck is the low ATK points of most "Venom" monsters. This means that your opponent can easily just Summon a monster to destroy your "Venom" monster. Because of this, cards like "Ambush Fangs" and "Negate Attack" are essential to this Deck.
- Another weakness of this Deck is "Zombie World". This card makes the ATK of "Vennominaga" become 0, and when it is destroyed by battle there are no Reptile-Type monsters in the Graveyard to banish in order to Special Summon it again. To stop this, "Field Barrier" can be used to prevent the opponent from playing a Field Spell Card, while also protecting your "Venom Swamp".
- The Deck relies on "Venom Swamp", so "Cursed Seal of the Forbidden Spell" will shut this Deck down.
- Since the Deck relies on Reptile-Type monsters being sent to the Graveyard, it is at its most vulnerable when banish strategies are used, like "Dimensional Fissure".
- "Venom" Decks are at risk of losing LP early, since the only reliable methods for quickly Summoning "Vennominon the King of Poisonous Snakes" from the Deck involve taking damage (either via "Damage = Reptile" or "Damage Condenser").