Augustin Thierry (or Jacques Nicolas Augustin Thierry; 10 May 1795 – 22 May 1856) was a French historian.
He was born in Blois, Loir-et-Cher, the elder brother of Amédée Simon Dominique Thierry. He had no advantages of birth or fortune, but was distinguished at the Blois Grammar School, and entered the École Normale Supérieure in 1811. In 1813 he was sent as a professor to Compiègne, but stayed there a very short time.
Thierry enthusiastically embraced the ideals of the French Revolution and Saint Simon's vision of an ideal future society. He became Saint-Simon's secretary and "adopted son"; but while most of Saint-Simon's followers applied his theories to present-day matters of political economy, Thierry turned to history instead.
Thierry was also inspired by Romantic literature, such as Chateaubriand's Les Martyrs, and Walter Scott's novels. Though Thierry did not actually write romances, his conception of history recognised the dramatic element (for instance, Les Martyrs dramatises the clash of the Roman Empire with Early Christianity).
Thierry's main ideas on the Germanic invasions, the Norman Conquest, the formation of the Communes, the gradual ascent of the nations towards free government and parliamentary institutions, are set forth in the articles he contributed to the Censeur européen (1817–20), and later in his Lettres sur l'histoire de France (1820). From Claude Charles Fauriel he learned to use primary sources; and by the aid of the Latin chronicles and the collection of Anglo-Saxon laws, he wrote Histoire de la Conquête de l'Angleterre par les Normands (History of the Conquest of England by the Normans), the appearance of which was greeted with great enthusiasm (1825). It was written in a style at once precise and picturesque, and was dominated by a theory of Anglo-Saxon liberty resisting the invasions of northern barbarians, and eventually reviving in the parliamentary monarchy. Notably, it is in this work that Thierry voices the belief that Robin Hood was a leader of the Anglo-Saxon resistance. His artistic talent as a writer makes the weaknesses and deficiencies of his scholarship less obvious. This work, the preparation of which had required several years of hard work, cost Thierry his eyesight; in 1826 he was obliged to engage secretaries and eventually became quite blind. Notwithstanding, he continued to write.