The Leviathans were a race of beings who ruled the Earth before mankind came into existence. Their forms were hideous and inhuman, although many Leviathans took human shape after they lost control of the planet. They longed to return to the Earth and reclaim it as their own (915). To that end they seized control of the mind of Barnabas Collins in 1796 before he could change history by leaving with and thereby saving his beloved Josette (886, 887).Paul Stoddard made a pact with the Leviathans, receiving wealth in return for what was dearest to him years later. Realizing this meant his daughter Carolyn, he sought to break the agreement (900).
In their efforts to take over the Collins family and ensure the marriage of Carolyn Stoddard to one of their own, they had Barnabas use the Naga Box, a wooden box with the power to enthrall humans into the Leviathan cult. This mystical device didn't always work however, due to resistant genetic structure in some people. Julia Hoffman was one of those unaffected (916), as was Maggie Evans (943).Nicholas Blair was an ally of the Leviathans, having originated the plan to resurrect the cult in the twentieth century (953).
The Leviathans were defeated when Jeb Hawkes, allied with Barnabas, destroyed the Naga Box during the ceremony to transform Carolyn Stoddard into a Leviathan. The Leviathan Altar and Jeb's true Leviathan form were destroyed by their actions. All members of the cult that had been enthralled during the recent events were subsequently released from Leviathan control with no memory of their participation in the group's activities (965, 966).
Many years later, Quentin Collins thwarted an attempt to resurrect the Leviathans when he returned The Crimson Pearl to the sea (see the Big Finish audio drama The Crimson Pearl) before the Pearl had absorbed enough energy to bring the Leviathans back into existence.
- Leviathans and members of the Leviathan cult included Oberon, Haza, Adlar, Barnabas Collins, David Collins, Jeb Hawkes, Amy Jennings, Sky Rumson, Elizabeth Collins Stoddard, Bruno, Nelle Gunston, Megan Todd, and Philip Todd.
- The Leviathans were suggested by the works of H.P. Lovecraft.