René Barrientos Ortuño (May 30, 1919 – April 27, 1969) was a Bolivian politician who served as his country's Vice President in 1964 and as its President from 1964 to 1969.

General Barrientos came to power by overthrowing the social reform government of Paz Estenssoro in an army backed coup. During his five-year rule, Barrientos and the army suppressed all opposition to his conservative regime, including a minor organized insurgency by Che Guevara in 1967.

Barrientos was a native of Tarata, department of Cochabamba, and was of mixed Quechua and Spanish descent. He was a career military officer, having earned his pilot's license in 1945. Later in the 1940s, he gravitated toward the reformist Revolutionary Nationalist Movement (Movimiento Nacionalista Revolucionario, or MNR) party of Víctor Paz Estenssoro. Barrientos played a part in the Bolivian Revolution of 1952, when the MNR toppled the established order and took power. In fact, he was given the honor of flying out of the country to bring back the revolutionary leader Víctor Paz Estenssoro, then in exile, once the rebellion succeeded. In 1957, Barrientos was rewarded when he was named commander of the Bolivian Air Force.

Known as a rather obsequious, sycophantic supporter of the MNR, he slowly became famous throughout the country for his uncommon, and very public, feats of valor. In 1960, for example, a live parachute-drop demonstration by Air Force soldiers ended in disaster when their equipment failed and three of the fifteen parachutists fell to their death before a large crowd assembled. Recriminations flew as to who may be held responsible for the carnage. Barrientos, then Air Force commander, decided to put a demonstration of his own and jumped from an airplane himself, using one of the parachutes that had failed to open during the earlier debacle. His point was that there had been nothing wrong with the equipment or the training, just bad luck, but the incident cemented his popularity among certain sectors of the population. Furthermore, the ruling MNR helped prop up his standing, as the MNR leadership constantly extolled general Barrientos' virtues as the paragon of the new kind of military officer the Revolution had fostered.

While around 1960 the ruling MNR party entered a phase of fragmentation due to personal and policy differences, Barrientos' stock was clearly on the rise. In addition, president Paz Estenssoro (elected to a second term in 1960) was leaning more heavily on military support to restore order to various parts of the country where rival pro-MNR militias had turned on each other, often on behalf of specific MNR leaders. Disarming the militias (who had been allowed to keep their weapons since the 1952 Revolution) became a priority to Paz, and this enhanced the role the "new" armed forces played in the national arena. The most popular of these military leaders was, of course, the dashing Barrientos.

In 1964, Paz Estenssoro had the Bolivian Constitution amended in order to be allowed to run for consecutive re-election, feeling that only he had the standing to keep the crumbling MNR together. Traditionally, attempts such as these (known as "prorroguismo") have been strongly condemned by the Bolivian political elites, many of whose members may have been waiting for their turn to occupy the presidential palace for years. This was no exception, and Paz's controversial move would soon prove harmful to him. Paz surprisingly chose general Barrientos as his running mate in that year's elections, and the two were sworn in in August, 1964. Just three months later, Barrientos — in tandem with the Army Commander Alfredo Ovando — toppled Paz in a violent coup d'état and installed himself as co-President in a Junta alongside general Ovando.

His idea all along was to capitalize on his popularity and run for elections, with the full support of the Bolivian military establishment now in control of the country. To this end, he resigned his co-presidency in early 1966 and registered himself as a candidate. With the most important civilian leaders (Paz, Hernán Siles, Juan Lechín) in exile, Barrientos was easily elected, and was sworn-in on August, 1966.

General Barrientos was quite charismatic, and was initially popular with ordinary Bolivians, aided by the fluency with which he spoke Quechua, the most important native language among the Bolivian peasantry. Barrientos enjoyed a loyal following among the poor farmers of Santa Cruz and Cochabamba and was one of the first South American leaders to engage in small scale farm mechanization. He cooperated with Frederick Pittera, an American inventor and manufacturer of small farm tractors at Keyser, West Virginia, who was endeavoring to introduce a new concept to eliminate world famine with his U.S. Patented small farm tractor equipment. The Food & Agriculture Organization of the UN had concluded through studies that small-scale mechanization was the only answer to eliminating world famine by helping the world’s malnourished poor to help themselves by growing their own food. FAO instead opted to daily feeding programs that fed only a small percentage of some 800 million hungry people around the world. According to Pittera, the effort was an abysmal failure and 25,000 people continue to die everyday. Pittera also secured the interest of President Alfredo Stroessner of Paraguay and General Juan Peron of Argentina as well, but military coups and exiles of these leaders crippled the project’s progress.

Barrientos was also skilled at manipulating the masses with his oratory, which often allowed him to present himself as both a populist and conservative, a revolutionary and a "law-and-order" advocate. Purporting to be a staunch Christian, Barrientos actively courted the Church and, in fact, chose as his running mate in the 1966 elections the leader of the small Christian Democrat Party of Bolivia, Dr. Luis Adolfo Siles. He was fiercely anti-Communist and pro-free market. Accepting more military aid and acquiescing to the training of special forces designed to combat possible Communist inspired insurgencies (under the aegis of the Alliance for Progress) made Barrientos particularly popular with Washington.

Barrientos had ample opportunity to prove his anti-Communist credentials in 1967, when a guerrilla force was discovered to be operating in the rural Bolivian southwest under the leadership of the Argentine-Cuban revolutionary Ernesto "Che" Guevara in the Bolivian mining camps. Barrientos was very concerned with Guevara's rising insurgency there, and clamped down in the area with some very heavy handed measures (such as the Massacre of San Juan). Guevara felt that such an atrocity by the Bolivian Army and Air Force would be the tipping point in his favour in rallying the miners to his Communist cause, but eventually the miners signed with government-owned mining company, Siglo XX, an agreement which Guevara felt undermined his reason for being there. The war between the Bolivian President Barrientos and Che Guevara's militia did not end there, but eventually the Bolivian Army Rangers captured Guevara and executed him in October 1967.

While temporarily enhancing the president's stature, this only started more troubles for Barrientos. While the army was fighting the guerrillas, the miners of Siglo XX (a state-owned Bolivian mining town) declared themselves in support of the insurgency, prompting the president to send troops to regain control. This led to the "Massacre of San Juan," when soldiers opened fire on the miners and killed around 30 men and women on Saint John's Day, called Día de San Juan in Spanish, June 24, 1967. Further, a major scandal erupted in 1968 when Barrientos' trusted friend and Minister of Interior, Antonio Arguedas, disappeared with the captured diary of Che Guevara, which soon surfaced in, of all places, Havana. From abroad, Arguedas confessed himself to have been a clandestine Marxist supporter, denouncing Barrientos and many of his aides as being on the CIA's payroll. The episode embarrassed the administration and cast doubts about the president's judgement (after all, it was he who was friends with, and had appointed, Arguedas to the most important ministry post in the government).

In the aftermath of the mining massacres and the rurthless anti-guerrilla campaign, Barrientos was widely seen by some as a brutal dictator at the service of foreign interests while masquerading as a democrat. Eager to do some damage control and repair his once excellent relations with the campesinos, Bolivian farm workers, the president took to traveling throughout the country to present his position, even to the smallest and remotest of Bolivian villages. It was a tactic that had yielded him good results in the past and Barrientos hoped to rebuild his political capital but when flying into Arque, Cochabamba Department, he perished on April 27, 1969, in a helicopter crash. Rumors persist to this day that the president's helicopter may have been sabotaged or shot down, however, all investigations concluded it had been an accident, with the rotors of the helicopter catching the electricity cables running through Arque canyon.