Fathom Five is the superhuman strike force that serves a renegade faction of Atlantean extremists called At'la'tique. Fathom Five consists of their leader Llyron, Sea Leopard, Bloodtide, Manowar and Dragonrider. They have been conducting terrorist attacks on the surface world in the name of At'la'tique to honor the teachings of Nagala and Shakkoth. The term At'la'tique first came into use four centuries ago by an Atlantean poet named Numara D'Athahr. He described it as the "fury of the sea," but its derivation was synonymous with respect for the power and majesty of the ocean's might. D'Athahr was a religious outcast and opposed the Atlantean monarchy. The name would be adopted by a growing band of fringe radicals who have driven a wedge into Atlantean society. Mistress Nagala appears to be the new leader of At'la'tique and employs the Fathom Five to attack the airlings and Namor's Atlantean troops.
Fathom Five was created by Kurt Busiek, Fabian Nicieza and Tom Grummett in 2004 and first appeared in New Thunderbolts # 1.
The Fathom Five's first public attack was on the city of New York where they were opposed by members of the resurrected Thunderbolts. Genis-Vell came to the aid of the Thunderbolts causing Fathom Five to retreat. Bloodtide was detained for a brief moment by Atlas and Genis-Vell, but she managed to escape when the two men started to fight each other. After their assault on Manhattan, political pressure from the surface world forced Prince Namor to commit Atlantean troops toward flushing out At'la'tique from their hiding place. The Fathom Five killed numerous Atlantean troops in the mountainous seabed region overlooking the canyons of Gel'then'amee as Mistress Nagala watched the massacre. Fathom Five once again attacked Manhattan and interrupted a quiet dinner between Abe Jenkins and his parole officer, Carol Danvers. Abe Jenkins was grounded because his Mach IV suit was damaged and watched Warbird fight off the Fathom Five by herself as he tried to help move civilians from danger. Radioactive Man, Speed Demon and Atlas came to Jenkins' aid after Warbird was hit with twenty thousand volts of electricity from Manowar. Warbird gave Jenkins her cell phone and provided a priority code and lockdown code which allowed him to retrieve his old Beetle suit in the C.S.A. storage. Jenkins put on his old armor which changed the tide to the Thunderbolt's favor. Each member of the Fathom Five was taken down and their leader Llyron was defeated when Radioactive Man used his powers to dehydrate him.
Baron Strucker and HYDRA attacked New York City after Fathom Five's defeat. During the chaos, Radioactive Man tossed the unconscious Llyron back into the ocean. After the HYDRA forces were defeated, some members of Fathom Five, including Bloodtide, Manowar and Dragonrider, were apprehended by the authorities, but Llyron and Sea Leopard escaped. Llyron was taken into custody by the Atlanteans and taken back to Atlantis. Several days later, the people of Atlantis started to become ill due to some form of radiation poisoning. Apparently, Radioactive Man irradiated Llyron's gills and every time he took a breath, he would release a radioactive agent into the waters around him. Radioactive Man wanted to take revenge for his people after thousands were killed by the At'la'tique terrorists.