Future Trunks (のトランクス 'Mirai no Torankusu') is the Saiyan and Earthling hybrid son of Future Vegeta and Future Bulma from an alternate future. By the time Present Trunks was born, the timeline had been altered by Future Trunks' and Cell's trips to the past. Therefore, the two Trunks had completely different lives (as opposed to those who lived before the Time Machines arrived, they lived exactly the same lives as their counterparts until the point at which the two timelines diverge: three years before the androids arrived).
Well-mannered, serious and very cautious, Trunks hails from an alternate timeline in which Future Androids 17 and 18 murdered the Dragon Team and proceeded to create apocalyptic hell on Earth.Trunks is trained by Future Gohan as a teenager and becomes a gifted fighter, swordsman and a Super Saiyan; traits that aid him greatly in the battle against the Androids after traveling back in time in order to save his own future.
For more information on this character, please visit their page on the Dragon Ball Wiki.