Guiron

Guiron acted as the guardian dog of two brain-eating space women, the last of a dead civilization on the planet Terra, and lived in a special hangar under a stream at the Terran Base. The aliens guided him with a mind control device. Before the Terrans revealed their true intentions, Guiron proved his combat prowess by effortlessly killing a Space Gyaos, reflecting its sonic cutter beam and literally slicing it to pieces with his blade. Guiron later fought Gamera, and nearly killed him as well, before returning to base. After the two kids activated the doors to Guiron's home, he once again came back from below ground, and destroyed the Terran Base. The fire given off by the burning buildings revived Gamera, who challenged Guiron to continue the fight. After a long fight in which Gamera used new acrobatic techniques to try and outsmart Guiron, Gamera eventually managed to defeat the knife headed beast by flipping him upside down - his blade stuck in the earth - then igniting a missile that had gotten stuck in his circular indents, blowing off the upper half of his body and killing him.