'Silver' Tiamat ('銀'のティアマト, 'Gin' no Tiamato) was the original Fourth Counterdragon, the predecessor of 'White' Leviathan and the previous holder of Code Vier, Antigravity. It was born to oppose the Fourth True Dragon, 'Heavy Tremor' Nova, and presumably succeeded in killing the fourth calamity, but perished at some point, causing Code Vier to be passed down to Leviathan.