Lee Harvey Oswald, Gavrilo Princip, Nathuram Godse and Sirhan Sirhan comprise the most famous assassins of political figures in the 20th century. Their murderous acts not only changed history but also guaranteed them everlasting infamy and a kind of immortality.

However, some prominent assassins have become forgotten in the mists of time -- one of them was born 100 years ago in Barcelona, Spain.

Jaime Ramón Mercader del Río, a Spanish communist and agent for Russia’s notorious NKVD intelligence agency, murdered Russian revolutionary Leon Trotsky in Mexico City in 1940 under orders from Joseph Stalin.

Trotsky, once one of the most powerful and influential members of the Russian Communist Party and founder and leader of the Red Army, grew dismayed by the rising power of Stalin in the 1920s in the wake of Vladimir Lenin’s death. Sensing a dire threat to his supremacy, Stalin removed Trotsky from power in 1927, forced him out of the party and deported him in 1929 to Turkey, where he remained for four years near Istanbul.

After brief (and harried) stays in France and Norway, the heavily guarded Trotsky eventually moved to Mexico, where he continued to oppose Stalin and his policies -- a stance that marked him for death.

Trotsky wrote prolifically in Mexico, including a book titled “The Revolution Betrayed,” a vitriolic attack on Stalinism. (This period coincided with the Great Terror in Russia, whereby Stalin purged tens of thousands of former communist party members, including sham trials, imprisonment and execution of many of Trotsky’s former Bolshevik allies.)

However, Trotsky’s years in Mexico were not entirely unpleasant -- he and his family resided in the Coyoacán neighborhood of Mexico City, where he became intimate with married painters Diego Rivera and Frida Kahlo. (Trotsky and Frida even had an affair.)

But Trotsky was living on borrowed time.

Enter Jamie Mercader.

Mercader’s Cuban-born mother, Eustaquia María Caridad del Río Hernández, who raised him alone in France, was an ardent communist and fanatical Stalinist who fought in the Spanish Civil War and also worked for the Soviet underground.

Caridad hailed from a wealthy and aristocratic landowning family in Cuba, while her husband, Pau Mercader, was a rich Catalan industrialist whom she quickly grew bored with and divorced. (As it turns out, “Mercader” means “merchant” in Catalan.)

Growing up in France, Mercader embraced his mother’s ideology, then worked for various leftist organizations in Spain and eventually came to the attention of NKVD recruitment officer Nahum Eitingon, who took him to Moscow to train as a Soviet agent.

Mercader’s road to his fateful encounter with Trotsky took some unexpected turns. While studying at the Sorbonne in Paris, he met Sylvia Ageloff, an American friend of Trotsky. As a Soviet spy, Mercader pretended he was Jacques Mornard, the son of a Belgian diplomat and a Trotskyite. Handsome, well-groomed and fluent in French and English, Mercader made a perfect spy for the Soviets.

The following year, Mercader followed Ageloff to the U.S., where he assumed the false identity of a Canadian name Frank Jacson.

By October 1939, Mercader moved (with his now-lover Ageloff) to Mexico City, where Trotsky and his family were living in exile. Trotsky had already survived prior assassination attempts by other Soviet agents. One of those agents, a man named Pavel Sudoplatov, claimed in his memoirs that, upon receiving the directive to kill Trotsky from Lavrenti Beria, Stalin’s fearsome chief of state security, he selected Mercader to carry out the murder of Trotsky.

Using Ageloff as a link, Mercader (as Jacson) befriended Trotsky, pretending to be a sympathizer in order to put the doomed man at ease.

Trotsky’s trust in Mercader eventually cost him his life -- on Aug. 20, 1940, Mercader attacked his host with an ice pick, failing to kill him. As Trotsky’s guards seized Mercader, Caridad and Eitingon (waiting outside in getaway vehicles) fled after Mercader failed to show up. Trotsky reportedly ordered his bodyguards not to immediately kill Mercader since he could provide answers behind the conspiracy to assassinate him.

But Trotsky died the next day in the hospital from brain injuries and blood loss.

Under questioning from Mexican police, Mercader claimed to be Jacques Mornard and alleged he quarreled with Trotsky because the Russian exile refused to bless his impending nuptials with Ageloff.

Mercader received 20 years in prison, while any charges against Ageloff were dropped.

According to a document written by Nick Lloyd for the Barcelona Metropolitan, Mercader’s true identity was not revealed until 1952, 12 years into his incarceration, when a Mexican prison guard overheard him singing a nursery rhyme in perfect Catalan (the language of his native Barcelona).

Upon Mercader’s release from prison in 1960 (after revealing nothing about his involvement in the conspiracy to kill Trotsky, claiming he acted alone), he was welcomed and feted in Cuba by new communist dictator Fidel Castro. The following year, he traveled to the Soviet Union, where Alexander Shelepin, head of the KGB (by then the dominant Russian intelligence agency) honored Mercader with the Hero of the Soviet Union award, the highest such decoration Moscow offered.

Mercader’s mother, the redoubtable Caridad, would work for the Cuban embassy in Paris until her death in 1975. Reportedly, she was fond of the luxurious life in France, although politically she remained a devout Stalinist.

Mercader would subsequently spend the rest of his life shuttling between Havana and Moscow until his death in Cuba in 1978. He was later buried in the Kuntsevo Cemetery in Moscow.

One year before his death, in 1977, Mercader wished to return to Spain, given that Fascist dictator Francisco Franco was dead and the Spanish Communist Party was legalized. Santiago Carrillo, then the general secretary of the Communist Party of Spain, who was seeking to break from Moscow, offered Mercader a chance to return home but only if he wrote his memoirs and revealed the identities of all Soviet agents working in Spain as well as their controllers in Moscow.

Mercader, a dedicated Stalinist till the very end, refused.

Trotsky’s grandson, Vsevolod Volkov, who as a boy came home to find his grandfather dying in his study, wrote many years later: “The plot [to kill Trotsky] proceeded in stages: Stalin, Beria, Eitingon ... Caridad Mercader and her son, the catalan Ramón Mercader (alias Jacson) were the people who murdered the founder of the Red Army and the comrade-in-arms of Lenin.”