The Leviathan was a massive Earth Empire mobile battlestation, which entered the Gemini System when the Directorate-Nyx fleet led by Michael Bonaparte released Starpoint from its stasis rift at the end of the main story. It is the final boss of Starpoint Gemini and its remake, Starpoint Gemini Origins. With its destruction, the Second Gemini War was ended, and the Empire's remnants led the Second Imperial Crusade, taking back Carthagena and cutting a bloody path through the center of Gemini.
The station was nearly as large as the Starpoint itself, and was so powerful it nearly completely destroyed the reborn Gemini League's fleet. After it was destroyed, the Imperial fleet crossed the Starpoint en-masse. General Paul Demetrius, the League's leader ordered everyone to retreat and to deactivate the T-Gate that connected The Twins (AKA Sector Zero) and The Junction, sacrificing his life to buy time for his allies to escape. Dmitry Khuzev succeded Demetrius as the League's commander, and the League became the Protectorate.
Starpoint Gemini Warlords revealed that the station was partially designed by Raynor Trace and Commander Blackwell, and the commander him/herself captained the ship in its final fight.
The Titans from the sequels and the Solari Concord's Proxima weapon were based on the Leviathan's technology, and is considered by the people of Gemini as the first of their kind.