Very little is known about Cottonmouth other than before he joined the Serpent Society, he was a common criminal in Mobile, Alabama. He was presumably enhanced by Roxxon Oil in order to gain superhuman abilities. He was then contacted by Sidewinder to join the criminal organization. During the mission to murder MODOK, Cottonmouth and his comrade Death Adder brutally attacked their target, and before Captain America was able to save him, the pair succeeded in killing him. Cottonmouth later attempted to kill Captain America alongside Rattler, Diamondback, and Death Adder, though he was eventually defeated and imprisoned. However, Sidewinder quickly freed Cottonmouth which allowed him to continue on with the Serpent Society.
Cottonmouth was created by Mark Gruenwald and Paul Neary in 1985 and first appeared in Captain America # 310.
Mayor Story Arcs
Cobra would take a job from Ghaur and Llyra to obtain four objects containing arcane mystic powers. Cobra would split up members of the Serpent Society and send them to various locations to retrieve these objects. Cottonmouth, Rattler, Bushmaster and Black Racer would come into conflict with Longshot, Psylocke, Storm and Dazzler of the X-Men over a magical rock located in Iceland. Cottonmouth attempts to bite off Psylocke's head but he gets hit by Storm's lightning bolt. The X-Men are teleported away into Mr. Jip's lair when they find all four mystical items. Cottonmouth and the rest of the Serpent Society are double crossed by Sidewinder and Diamondback, leaving them broke and battered.
Erik Killmonger would hire Boss Morgan to eliminate the Black Panther in the United States. Morgan gathers a group of criminals that include Cottonmouth, Nightshade, Cockroach Hamilton, and Stiletto for this assignment. However the Black Panther is backed up by some of his friends, Luke Cage, Iron Fist, Falcon and Bill Foster. During the fight, Cottonmouth clamps onto Cage's arm but he is unable to pierce his steel-hard skin. Cottonmouth and the rest of his fellow cronies fail to kill Black Panther and are defeated. He also briefly allied himself with Hawkeye, Plantman, and Headlok to escape from prison.
The Desert Stars would run into American Eagle after Cottonmouth entered an Indian reservation in Arizona. Cottonmouth just robbed a bank in Phoenix and the Desert Stars were in close pursuit. Cottonmouth escaped and was hiding on Indian territory after kidnapping a young girl and killing some dogs. The Desert Stars no longer had jurisdiction in Navajo Nation and the authorities had their own hero to deal with the craziness. American Eagle would defeat Cottonmouth and force him to bury the people he killed on the reservation.
An open contract was placed on Staff Sergeant Marcus Johnson and was wanted dead or alive because his blood was needed by Orion, the former leader of LEVIATHAN. Johnson came into conflict with other contracted enemy agents like Deadpool and Taskmaster. Johnson found himself surrounded by Cottonmouth and the Serpent Society during his fight with Taskmaster at a construction site. Johnson tried his best to fight back but was simply overwhelmed and finally struck down by Rattler's tail. Cottonmouth wanted to bite off the head of Johnson until he was shot in the head by Deadpool. The rest of the Serpent Society were placed under arrest by SHIELD.
Avengers vs X-Men
Cottonmouth and several members of the Serpent Society break into the Isotope Bank in San Francisco and hold several people hostage. Hope Summers responds to the police call and flies to the bank on her own. Cottonmouth and Anaconda stay with Puff Adder as he works on the vault door with his acidic spit. Hope would take out Bushmaster and Asp before confronting the rest of the Serpent Squad. Hope easily takes down Puff Adder and Anaconda and pummels away on Cottonmouth until Cyclops and the other X-Men arrive on the scene.
Cottonmouth would be involved in a story taking place in the Marvel Adventures comics which are standalone stories and does not take place in the current Marvel Universe continuity.
Cottonmouth and the Serpent Society would kidnap Dr. Curt Connors when they learn the truth about his Lizard formula and forced him to experiment on innocent civilians. The Serpent Society had Dr. Connors modify his formula and had plans to contaminate the water supply in New York so everyone would transform into humanoid lizards. However their plans were thwarted by Spider Man so Cottonmouth and the rest of the Serpent Society retreated when Connors ingested his own formula and transformed into a giant Lizard.