Livio the Double Fang is a character from the anime Trigun Stargaze who serves as the final member of the Gung-Ho Guns, a group of assassins aligned with the Eye of Michael. He is introduced as a childhood friend of Nicholas D. Wolfwood, having grown up alongside him in the same orphanage. During his youth, he was known by the nickname Livio the Crybaby due to his sensitive and timid nature. As an adult, he is characterized as a polite and gentle person who treats others with respect, though he carries deep emotional wounds from a traumatic upbringing. His personality contrasts sharply with that of his alternate identity, Razlo the Tri-Punisher of Death, a violent and psychotic split personality who emerged as a psychological defense mechanism. Razlo was created to absorb the abuse inflicted by Livio's father, allowing Livio himself to remain unaware of the mistreatment. Razlo typically surfaces only when Livio experiences intense pain or violence and is responsible for extremely destructive acts, including the murder of Livio's parents.

Livio's motivations initially stem from his indoctrination within the Eye of Michael and his role as a member of the Gung-Ho Guns, following orders without deeper questioning. However, his true drive becomes intertwined with his relationship with Wolfwood and his struggle to reconcile his fractured self. In the story, Livio plays a pivotal role in the latter half of the series, acting as both an antagonist forced into conflict with his former friend and a tragic figure shaped by forces beyond his control. His most significant confrontation occurs when he faces Wolfwood, who ultimately sacrifices his own life by overdosing on a regeneration drug to defeat Razlo and protect Livio. This loss becomes the turning point for Livio. In the aftermath, he acknowledges Razlo as part of himself and declares that he is now strong enough to face life on his own without relying on his violent alter ego. Razlo recedes into the background of his mind.

Seeking redemption, Livio is forgiven by Vash the Stampede and becomes Vash's partner, striving to live as Wolfwood would have wanted. He later confronts Elendira the Crimsonnail and, realizing he cannot win alone, allows Razlo to reemerge temporarily, using Razlo's faster reflexes and superior eyesight to defeat the enemy. After these events, Livio settles at his old orphanage, caring for the children there, and is shown paying respects at Wolfwood's grave. He is a hard worker who relies on discipline and effort, a contrast to Razlo's innate talent and cruelty.

In terms of abilities, Livio wields the Double Fangs, two compact cross-shaped sub-machine guns with dual barrels that allow them to fire forward and backward simultaneously. These weapons are typically strapped to his wrists, and later he carries them in low-slung shoulder holsters. His body has undergone enhancements that increase his metabolic rate, granting him the ability to recover from near-fatal wounds in a matter of seconds. Razlo, when in control, wields three Punishers, the same type of heavy firearm used by Wolfwood, aided by a bionic arm and supported by three servants who carry the weapons.