Friedrich von Gentz (2 May 1764 – 9 June 1832) was a Prussian-Austrian diplomat and a writer. With Austrian chancellor Klemens von Metternich he was one of the main forces behind the organisation, management and protocol of the Congress of Vienna.

Von Gentz was born in Breslau. His father was an official, his mother was from the distinguished Berlin Huguenot family Ancillon and the aunt of Prussian minister Friedrich Ancillon. On his father′s transfer from Breslau to Berlin as director general of the royal mint, the gifted boy was sent to the Joachimsthalsches Gymnasium there. At the University of Königsberg he got acquainted with the teachings and thinking of Immanuel Kant, his intellect was sharpened and his zeal for learning quickened by the great thinker's influence. Nevertheless Kant′s categorical imperative and his ideas on the commandment of reason, from which all duties and obligations derive, did not prevent von Gentz from yielding to the taste for wine, women and gambling.

When in 1785 he returned to Berlin, he received the appointment of secretary to the royal Generaldirectorium, his brilliant talents soon gaining him promotion to the rank of councillor for war (Kriegsrath). During an illness, which kept him virtuous by confining him to his room, he studied French and English, gaining a mastery of these languages, which opened up for him opportunities for a diplomatic career.

His interest in public affairs was, however, first aroused by the outbreak of the French Revolution. As a quick-witted young man, he greeted it with enthusiasm, but its subsequent developments cooled his ardour and he was converted to more conservative views by Burke's Reflections on the Revolution in France, the translation of which into German (1794) was his first literary venture. This was followed, the next year, by translations of works on the Revolution by Mallet du Pan and Mounier, and he also founded and edited a monthly journal, the Neue deutsche Monatsschrift in which, for five years he wrote, mainly on historical and political questions. He maintained the principles of British constitutionalism against those of revolutionary France. The knowledge that he displayed of the principles and practice of finance was especially remarkable. In 1797, at the instance of English statesmen, he published a translation of a history of French finance by François Divernois (1757–1842), an eminent Genevese exile naturalized and knighted in England, extracts from which he had previously given in his journal. His literary output, all inspired by a moderate liberalism, was astounding, and it included an essay on the results of the discovery of the Americas, and another, written in French, on the English financial system (Essai sur l'état de l'administration des finances de la Grande-Bretagne, London, 1800). Especially noteworthy, however, was the Denkschrift or Memorandum he addressed to King Frederick William III on his accession (1797), in which, inter alia, he urged upon the king the necessity for granting freedom to the press and to commerce. For a Prussian official to venture to give uncalled-for advice to his sovereign was a breach of propriety not calculated to increase his chances of favour, but it gave von Gentz a conspicuous position in the public eye, which his brilliant talents and literary style enabled him to maintain. Moreover, he was from the first aware of the probable developments of the Revolution and of the consequences to Prussia of the weakness and vacillations of her policy.

Opposition to France was the inspiring principle of the Historisches Journal founded by him in 1799 and 1800, which once more held up English institutions as the model, and he became in Germany the mouthpiece of British policy towards the revolutionary aggressions of the French Republic. In 1801, he ceased the publication of the Journal because he disliked the regularity of journalism. He issued instead, under the title Beiträge zur Geschichte, etc., a series of essays on contemporary politics. The first was Über den Ursprung und Charakter des Krieges gegen die französische Revolution (1801), regarded by many as Gentz's masterpiece; another important brochure, Von dem politischen Zustande von Europa vor und nach der Revolution, a criticism of Hauterive's De l'ėtat de la France de la fin de l'an VIII, appeared the same year.

He gained recognition abroad and gifts of money from the British and Austrian governments, but it made his position as an official in Berlin impossible, as the Prussian government had no mind to abandon its attitude of cautious neutrality. Private affairs also combined to urge von Gentz to leave the Prussian service; mainly through his own action, a separation with his wife was arranged. In May 1802, accordingly, he took leave of his wife and left with his friend Adam Müller for Vienna. In Berlin, he had been intimate with the Austrian ambassador, Count Stadion, whose good offices procured him an introduction to the Emperor Francis. The immediate result was the title of imperial councillor, with a yearly salary of 4000 gulden (6 December 1802), but it was not until 1809 that he was actively employed. Before returning to Berlin to make arrangements for transferring himself finally to Vienna, von Gentz paid a visit to London, where he made the acquaintance of Pitt and Grenville, who were so impressed with his talents that in addition to large money presents, he was guaranteed an annual pension by the British government in recognition of the value of the services of his pen against Napoleon Bonaparte.

From then on, he was engaged in a ceaseless polemic against every fresh advance of Napoleonic dictatorial power and pretensions. With matchless sarcasm he lashed the nerveless policy of courts that suffered indignity with resignation. He denounced the recognition of Napoleon's imperial title and drew up a manifesto of Louis XVIII against it. The formation of the coalition and the outbreak of war, for a while, raised his hopes despite his lively distrust of the competence of Austrian ministers. Hopes were speedily dashed by the Battle of Austerlitz and its results. Von Gentz used his enforced leisure to write a brilliant essay on The relations between England and Spain before the outbreak of war between the two powers (Leipzig, 1806). Shortly afterwards appeared Fragmente aus der neuesten Geschichte des politischen Gleichgewichts in Europa (translated as Fragments on the Balance of Power in Europe, London, 1806). The last of von Gentz's works as an independent publicist, it was a masterly exposé of the actual political situation and was also prophetic in its suggestions as to how this should be retrieved: ″Through Germany Europe has perished; through Germany it must rise again″.

He realized that the dominance of France could not be broken but by the union of Austria and Prussia, acting in concert with Britain. He watched with interest the Prussian military preparations. At the invitation of Count Haugwitz, he went at the outset of the campaign to the Prussian headquarters at Erfurt, where he drafted the king's proclamation and his letter to Napoleon. The writer was known, and it was in this connection that Napoleon referred to him as a ″wretched scribe named Gentz, one of those men without honour who sell themselves for money″. Von Gentz had no official mandate from the Austrian government, and whatever hopes he may have cherished of privately influencing the situation in the direction of an alliance between the two German powers were speedily dashed by the Battle of Jena.