The assembled form of a retrovirus that fuses with other lifeforms and corrupts them into evil monsters. Gudis wishes to destroy all life within the universe. Ultraman Great refers to it as “The destroyer of the universe”.

Gudis was challenged to a fight by Ultraman Great on Mars and used its long tentacles to knock the Ultra unconscious. Next, Gudis used its tentacles to destroy an Australian Space Development Agency research spaceship that flew to Mars. Gudis then fought against Great again after he regained consciousness. At first, the virus monster resisted the Ultra’s punches and kicks, but was knocked over by Great’s Burning Plasma attack, and then broken down molecularly by Great’s Dissolver ray.

However, Gudis’ cells were still intact, and the virus escaped from Mars in cell form. The virus flew to Earth and became “Gudis Cells” which fell over the South Pacific. They infected lifeforms on Earth, created paranormal phenomena to occur, and gave birth to various monsters.