Leviathan

Leviathan is a mythical creature believed to have the power to kill a Reaper and the focus of Mass Effect 3: Leviathan. During the Reaper invasion in 2186, Admiral Hackett orders Task Force Aurora to pursue myths with any relation to the Reapers, such as Leviathan, in the hopes of discovering the means to stop them.

Leviathan is voiced by Anthony Skordi.

Leviathan
After Dr. Garret Bryson's death, it is revealed from a recorded conversation between Bryson and Admiral Hackett that Leviathan is believed to be the entity that killed the Leviathan of Dis approximately one billion years ago.