Jaume Ramon Mercader del Rio Hernández (February 7 1914 – October 18 1978) was a Spanish Communist who became famous as the murderer of Leon Trotsky. Although declassified archives have shown that he was a Soviet agent, supporters of Stalin continue to argue that he was simply a disgruntled former follower of Trotsky.

Mercader was born in 1914 in Barcelona, but spent much of his youth in France with his mother, Eustacia María Caridad del Río Hernández, after she separated from his father, Don Pablo Mercader Marina. As a young man, he embraced Communism, working for leftist organizations in Spain during the mid-1930s. He was briefly imprisoned for his activities, but was released in 1936 when the left-wing coalition Popular Front won the democratic election.

Mercader befriended Silvia Ageloff, an unmarried secretary of Trotsky's. Through her, he began to meet with Trotsky personally, as a Canadian supporter of Trotsky's ideas. On August 20, 1940 Mercader fatally wounded Trotsky with an ice axe in his study at his home in Coyoacán (then a village on the southern fringes of Mexico City). Trotsky's guards burst in and nearly killed Mercader, but were ordered by Trotsky to spare his life, yelling, "Do not kill him! This man has a story to tell."

He was turned over to the Mexican authorities, to whom he refused to give up his real identity. He would only identify himself as Jacques Mornard, claiming to be the son of a Belgian diplomat. Nevertheless, he was convicted of murder and sentenced to 20 years in prison.

After the first few years in prison, he requested release on parole, which was denied by Dr. Jesús Siordia and criminologist Alfonso Quiroz Cuarón. After almost 20 years in jail, he was eventually released from Mexico City's Palacio de Lecumberri prison on May 6, 1960 and moved to Havana, where Fidel Castro's new revolutionary government welcomed him. In 1961, he moved to the USSR and was awarded the Hero of the Soviet Union medal — the country's highest decoration — one of only twenty-one non-Soviet citizens to receive the award. He split his time between Cuba and the USSR for the rest of his life and died in Havana in 1978.

He is buried (under the name of Ramon Ivanovich Lopez) in Moscow's Kuntsevo Cemetery and has a place of honor in the KGB museum in the Russian capital.

*The sleeper assassin in the novel and film The Manchurian Candidate is named Raymond. He has been programmed by his mother, a Soviet agent, to follow orders unflinchingly. *A play by David Ives entitled Variations on the Death of Trotsky is a comedy based on Mercader's assassination of Trotsky.

*Asaltar los Cielos (A Spanish documentary about the life of Ramón Mercader