Robert Coulondre (11 September 1885 – 6 March 1959) was a French diplomat who served as the last French ambassador to Germany before World War II.

From Nîmes to Geneva Coulondre was born in Nîmes, the son of the politician Gaston Coulondre. As the Coulondres were a Protestant family, they were very loyal to the republic with its principles of Liberté, Égalité, Fraternité for all people. French Protestants had been oppressed under the ancien-regime following the revocation of the Edict of Nantes in 1685, and for Protestants the French Revolution with its promise of a secular society and Liberté, Égalité, Fraternité was very attractive. After obtaining a university degree in Chinese, he joined the Quai d'Orsay in 1909. Coulondre was stationed in London in May 1909, was appointed attaché at the Foreign Minister's office in March 1912 and became assistant consul in Beirut in 1912. In August 1914, as World War I started, Colondre was commissioned as a lieutenant in the 117th Infantry Regiment. On 13 September 1914 he won the Croix de Guerre and the Legion of honor for bravery in an action against the invading Germans. In November 1915, he was transferred from the Western Front to the Armées alliées en Orient which had landed in the Greek city of Salonika to start an offensive to support Serbia. The diplomat François Georges-Picot recruited Coulondre, a fluent Arabic speaker who had formally served in Beirut to serve as one of his agents in the Middle East. In 1916, he was appointed the French representative to the Arab Office in Cairo that was supporting the Great Arab Revolt in the Hejez against the Ottoman Empire. Coulondre helped negotiate the Sykes-Picot agreement of May 1916 laying out the British and French spheres of influence in the Middle East after the anticipated defeat of the Ottoman Empire. In 1917–1918, Coulondre served alongside the diplomats Louis Massignon and Charles Maugras on the Sykes-Picot mission laying the borders between the spheres of influence.

In October 1918, Coulondre protested on behalf of France against the actions of the Emir Faisal in attempting to occupy all of Lebanon while asking Paris to dispatch the French Navy to land marines in the coastal cities of Lebanon "before it was too late". Coulondre also delivered a protest to the Emir Faisal, pointing out the Sykes-Picot Agreement had assigned Lebanon to France, leading Faisal to claim his reasons for sending the Arab Northern Army into Lebanon were "purely military". A British attempt to persuade Coulondre to accept the authority of Shurki al-Ayubi, Faisal's governor in Lebanon, as a civil governor under French military authority, was unsuccessful while Coulondre insisting that mostly Christian Lebanon was in the French sphere of influence and he would not have Faisal's representatives from the Muslim Hejaz playing any role in Lebanon. Coulondre met with Field Marshal Sir Edmund Allenby, who apologised to him, insisting it was all a "misunderstanding", and ordered Ayubli out of Beirut on the night of 10 October 1918. The next day, the flag of the Hejaz was lowered while the French tricolor was raised over Beirut. On 16 October 1918, Coulondre told Gilbert Clayton that France wanted to occupy the Beqaa Valley in accordance with the Sykes-Picot Agreement, which was rejected by the British who assigned the valley to Faisal's agents. For the next two years, an uneasy truce prevailed with Faisal insisting that the Lebanese were Arabs and belonged in his state while the French argued that the Maronite Christians did not want to join a Muslim-dominated state. In May 1919, he married Pauline Meyer and was sent to Rabat, Morocco as the French consul. In November 1920, he went to Paris to join the Commercial Relations Sub-Department of the Quai d'Orsay.

In January 1926 he was a delegate to Franco-Soviet economic negotiations. French investors have been by far the largest buyers of Russian bonds issued before 1917 and had invested the most capital in the Russian Empire, and thus were the ones most hurt by the nationalisations carried out by the Soviet regime and by the debt repudiation of 1918, the largest debt repudiation of all time. A key problem in Franco-Soviet relations in the 1920s was the French demand that the Soviet Union honor the debts repudiated in 1918 and pay compensation to the French investors whose assets in Russia had been nationalised without compensation, demands that the Soviet government consistently rejected. From 1927 to 28 February 1933, he headed the Commercial Relations Department of the Political and Commercial Directorate and subsequently Deputy Director of the Political and Commercial Directorate at the Quai d'Orsay working under the Political Director René Massigli. Coulondre was a member of the "Protestant clan" that dominated the Quai d'Orsay in the first part of the 20th century. From 1920 to 1936, Coulondre had closely studied the German economy and in 1931 when the premier, Pierre Laval, visited Berlin to discuss the crisis caused by the collapse of the banks in Central Europe, Coulondre had accompanied him as an adviser.

The leading members of the "Protestant clan" were Coulondre, René Massigli, Victor de Lacroix, Albert Kamerer, Jacques Seydoux de Clausonne and his son François Seydoux de Clausonne, all of whom knew each other and worked closely together. Since French Protestants were persecuted under the ancien-regime when the state religion was Roman Catholicism, French Protestants tended to be very supportive of the legacy of the French Revolution. The "Protestant clan" in the Quai d'Orsay were all supporters of the republic and its values of Liberté, Égalité, Fraternité in domestic affairs while favoring a rule-based international order, support for the League of Nations, opposition to appeasement, and an abhorrence of Nazi Germany as the antithesis of everything they believed in.

In 1935, as the French delegate to the League of Nations, he pressed for more raw materials to be included in the sanctions applied against Fascist Italy for invading Ethiopia. On 17 October 1935, he pressed the Canadian delegate to the League of Nations in Geneva, Walter Alexander Riddell, to have nickel added to the sanctions list, to the oblivious discomfort of Riddell as nickel was a major Canadian export. Riddell refused to add nickel to the sanctions list, despite Coulondre pressing him on that point. Coulondre reported to Paris that Riddell had told him that Canada "would not put forward any definite motion as to specific materials, but did note that such materials included should be embargoed in all forms." In response to the demand to add iron to the sanctions list, Coulondre met with Riddell and the South African delegate, Charles Te Water to make a proposal to add the derivatives of iron to the sanctions list, only for Riddell to prevaricate on the issue. Coulondre suggested that either Te Water or Riddell propose that derivatives from iron be added to the sanctions list. On 19 October 1935, in response to a protest from the Spanish delegate Salvador de Madariaga about the exclusion of finished iron from the sanctions list, Coulondre stated that the major iron producers such as the United States were not members of the League. In a speech on 2 November 1935, Coulondre argued that adding steel to the sanctions list was "through logical, but not practical", and that allowing Italy to import finished steel would damage the Italian economy by forcing the Italian government to use up its foreign exchange than by adding steel to the sanctions list.

Ambassador in Moscow Mission to the Kremlin In 1936, he was appointed the French ambassador to the Soviet Union. The Quai d'Orsay was one of the most prestigious branches of the French state, and ambassadors were an elite group within the Quai d'Orsay, having the right to be addressed as "your excellency", to wear a ceremonial embodied uniform that was meant to impress and since ambassadors represented the president of the republic, in theory ambassadors outranked the foreign minister in protocol. Between 1932 and 1939, only 30 diplomats were promoted up to the rank of ambassador, making Coulondre part of a very select group. Coulondre went to Moscow with two guiding principles with the first being that Nazi Germany was a menace that had to be stopped and the second being that the best way to do that was an alliance with the Soviet Union. Coulondre was chosen as the ambassador to Moscow by the Popular Front government of Léon Blum, who felt that an experienced diplomat well known for calling for closer ties to Moscow was the ideal man to represent France to the Kremlin. Coulondre later wrote that the Quai d'Orsay's information about the Soviet Union was almost non-existent as discovered looking through the files "that relations with the USSR, established in 1924, had been neither very close nor very well cultivated since then, notwithstanding the pacts".

Coulondre described his superior, the Foreign Minister, Yvon Delbos, as being paranoid about the Soviets and fearful that the alliance that France had signed with the Soviets in 1935 was merely a device which Joseph Stalin might use to "push" France into a war with Germany. Delbos in giving his instructions to Coulondre openly wondered aloud "...whether they [the Soviets] were not looking to push us into a conflict with Germany". Delbos further stated that if war with came with Germany, France was destined to lose because: "If defeated it [France] would be Nazified. If victorious, it must, due to the destruction of German power, submit, with the rest of Europe, to the overwhelming weight of the Slavic world, armed with the communist flamethrower". Coulondre recalled in his 1950 memoirs De Staline à Hitler Souvenirs de deux ambassades, 1936-1939 that "the presentation of his [Delbos's] statement was made completely in a negative sense". Coulondre was told in his instructions that there was no question of a "preventive war" to put an end to the Nazi regime while its rearmament had just started, and he would was to refuse any Soviet offer about a "preventive war"; that he must end Soviet involvement in French internal affairs; and should a war come, he was to discuss "possible military aid" to the Soviet Union.