A character in Trigun, Legato Bluesummers is a slender young man with silver hair and a soft voice, and is the leader of the Gung Ho Guns. He hates humanity and looks forward with great anticipation for the day that they all die. His history remains unrevealed, at least in the anime (it's probable that the manga based on the TV series, called Trigun Maximum, goes into it a bit more). Given this lack of information, it's hard to say how he gained his powers, why he detests everyone so much, or how he became leader of the Gung Ho Guns.
Legato is by far the most dangerous of the Gung Ho Guns. He has the power to take control of someone's body at will, using them as his weapons. At times he also uses innocent people as messengers, using them to give a chilling message
to the recipient before the messenger drops dead of terror. Considering his inclinations and capabilities, one might think there would be a bloodbath wherever he went. On the contrary, he keeps to himself most of the time, eating tasty food (he is seen eating hot dogs, pancakes, and doughnuts at various times in the series) and watching the people he wants dead as they go about what he sees as their pointless existence. Once, he indulged himself by killing a group of several hundred bandits who annoyed him while he was eating his pancakes; some were killed by their own - unwilling - hands.
Warning: Spoilers Ahead
Legato, though the gun hand of Chapel the Evergreen, killed Nicholas D. Wolfwood. Chapel, angered at being forced to kill his protoge, attempted to take revenge on Legato. The extemely likely outcome of this fight would have been Chapel's death by his own hand, but instead Knives appeared and swiftly dispatched Chapel with what appeared to be a minature black hole.
He dies at the hand of Vash the Stampede. Two of Vash's friends, Millie Thompson and Meryl Strife, were about to be killed by villagers under his control. Vash was given the options of watching them be killed, or kill Legato. Indeed, Legato wanted Vash to kill him, because his master, Knives, wanted Vash to experience suffering and doubt. Given that Vash bases his entire existence on not killing anyone, no matter what, Legato
and Knives certainly got what they wanted when Vash shot Legato in the head.