He was reportedly born in year 10, 140 of the Imperial system of dating. That is 10, 140 years after the formation of the Spacing Guild. His father was reigning Duke of House Atreides. Their family had ruled planet Caladan for 26 generations. They were related to the Imperial House Corrino and were in constant conflict with House Harkonnen.
His father had been a famed bullfighter. He was already in his old age when a bull managed to kill him. Leto kept a portrait of his father and the head of the animal as a reminder of this event. Leto was eventualy married to the Bene Gesserit acolyte Lady Jessica also known later as Jessica Atreides. Unknown to him was that Jessica was an illegitimate daughter of his rival Vladimir Harkonnen. By all accounts, Leto was a passionate husband to his wife. In year 10, 176 they had Paul Atreides, their first son.
Leto was widely known as "the Red Duke" and gained fame as an effective politician and a competent leader to his small army. He had managed to recruit famed individuals such as Thufir Hawat, Gurney Halleck and Duncan Idaho to serve under him and train his soldiers. Jessica and Hawat also served as his two main advisors. Leto was equaly feared by the Emperor Shaddam Corrino IV and hated by his longtime rival Vladimir Harkonnen.
In year 10, 191 the two conspired against him. Leto was forced to surrender Caladan to Vladimir and receive Arrakis instead. His term as Duke of Arrakis would proove short. He was betrayed by Dr. Wellington Yueh, his family physician and surrendered alive to Vladimir. Yueh in fact hated Vladimir as he was responsible for the death of his wife. But he had been unable to find ways to approach him. His plot went further than Vladimir suspected. He had provided Leto with a false tooth filled with poison. When released it would kill Leto and all those near him. He hoped those would include Vladimir. Leto indeed chose to die rather than face torture. But the one to die with him was actually sadistic mentat Piter De Vries. Leto was 51 years old.
Leto was survived by Jessica and Paul. Jessica was pregnant at the time of his death. Eight months later she would give birth to Alia Atreides. His grandson would later be named Leto Atreides II.