Valiaro is reputed in myth to have been the first Cybertronian to be created specifially to combat the demons. He was the most bloodthirsty and aggressive of the Firstforged - some legends credit him with severing Maximo's left hand - and the most skilled in close combat. He was the inventor of close-combat arms and armour. Valiaro was the seventh of the Firstforged and his spawnlings were called the Valovancarons. His line of descent the now-extinct Valovincians. According to legend Valiaro demerged from the bed of the Sea of Rust, and the burning pain from the corrosive sea caused him to struggle so hard he upheaved the Hydrax plateau from the floor of the ocean.

It is believed he died in combat with the demons, weighed down by several thousand and then eaten alive. By this the demons absorbed his power and became strong enough to overcome the Second Generation, leading to the near-extinction of the Cybertronians and the final sacrifice of Prima.

The name "Valiaro" meaning "valiant warrior", is a translation of the meaning of his name in Ancient Cybertronian. In Primaltongue he was called Karuch-O-Kyrax meaning "I exist, I hurt, I act from pain". In Modern Autobot he is called Kauto-Kasakar meaning "the skilled fighting master whose future is prepared", the latter part of which refers to Valiaro's courage and fearlessness in the face of death. This part of his name has become so iconic that it has given rise to the Autobot word kasakar. Literally translated this means "I am future's master", however it can be used as a figure of speech roughly meaning "Let battle be joined". When spoken as a challenge it indicates an intention to fight to the bitterest end.

Kauto-Kasakar is transliterated into Murion as Kardi-Troshe-Kiar. In High Legion he was called Uwadu-osase-cuas-wamya'te-ase, meaning "ambitious lord of fear, driven by pain and rage". More literally it refers to uwado and means "uwado is the driving force of the ambition of the fearsome lord". In Modern Decepticon he is called Khryaranterakar, meaning "lord of steel and rage-pain, he prepared his future". This describes Valiaro as a ruler of both khyran [physical warfare, in the form of steel] and khyuar [a Decepticon concept similar to uwado, in which rage and pain unite to form an emotional drive likened to a nuclear fire, which fuels the will to live and fight]. This has strong connotations of balance or even-handedness. Whilst the High Legion name for Valiaro is one of great fear, the Modern Decepticon name is one of high respect.