Johann Christian Friedrich Hölderlin (German pronunciation: [ˈjoːhan ˈkʁɪsti.aːn ˈfʁiːdʁɪç ˈhœldɐliːn]; 20 March 1770 – 7 June 1843) is a major German lyric poet, commonly associated with the artistic movement known as Romanticism. Hölderlin is also an important thinker in the development of German Idealism, particularly his early association with and philosophical influence on his seminary roommates and fellow Swabians Georg Wilhelm Friedrich Hegel and Friedrich Wilhelm Joseph Schelling.
Hölderlin was born in Lauffen am Neckar in the Duchy of Württemberg. His father, the manager of a church estate, died when the boy was two years old. He was brought up by his mother, who in 1774 married the Mayor of Nürtingen and moved there. He had a full sister, born after their father's death, and a half-brother. His stepfather died when he was nine. He went to school in Denkendorf and Maulbronn and then studied theology at the Tübinger Stift, where his fellow-students included Georg Wilhelm Friedrich Hegel, Friedrich Wilhelm Joseph Schelling (who had been a fellow-pupil at his first school) and Isaac von Sinclair. It has been speculated that it was probably Hölderlin who brought to Hegel's attention the ideas of Heraclitus about the union of opposites, which the philosopher would develop into his concept of dialectics. Finding he could not sustain a Christian faith, Hölderlin declined to become a minister of religion and worked instead as a private tutor. In 1793-94 he met Friedrich Schiller and Johann Wolfgang Goethe and began writing his epistolary novel Hyperion. During 1795 he enrolled for a while at the University of Jena where he attended Fichte's classes and met Novalis.

As a tutor in Frankfurt from 1796 to 1798 he fell in love with Susette Gontard, the wife of his employer, the banker Jakob Gontard. The feeling was mutual, and this relationship was the most important in Hölderlin's life. Susette is addressed in his poetry under the name of 'Diotima'. Their affair was discovered and Hölderlin was harshly dismissed. He lived in Homburg from 1798 to 1800, meeting Susette in secret once a month and attempting to establish himself as a poet, but was plagued by money worries, having to accept a small allowance from his mother. He worked on a tragedy in the Greek manner, Empedokles, producing three versions, all unfinished. Already at this time he was diagnosed as suffering from a severe "hypochondria", a condition that would worsen after his last meeting with Susette Gontard in 1800. After a sojourn in Stuttgart, probably working on his translations of Pindar, at the end of 1800 he found further employment as a tutor in Hauptwyl, Switzerland and then, in 1802, in Bordeaux, at the household of the Hamburg consul. His stay in that French city is celebrated in "Andenken" ("Remembrance"), one of his greatest poems. In a few months, however, he returned home on foot via Paris (where he saw Greek sculptures for the only time in his life). He arrived home in Nürtingen both physically and mentally prostrated. Susette died from influenza in Frankfurt about the same time.

After some time in Nürtingen he was taken to the court of Homburg by Sinclair, who found a sinecure for him as court librarian, but in 1805 Sinclair was denounced as a conspirator and tried for treason. Hölderlin was in danger of being tried too but was declared mentally unfit to stand trial. The state of Hesse-Homburg was dissolved the following year after the Battle of Jena. On 11 September Hölderlin was delivered into the clinic at Tübingen run by Dr Ferdinand Autenrieth, inventor of a mask for the prevention of screaming in the mentally ill. The clinic was attached to the University and the poet Kerner, then studying medicine, was assigned to look after Hölderlin for a while. The following year he was discharged as incurable and given three years to live, but was taken in by the carpenter Ernst Zimmer (a cultured man, who had read Hyperion) and given a room in his house in Tübingen, which had been a tower in the old city wall, with a view across the Neckar river and meadows. Zimmer and his family cared for Hölderlin until his death in 1843, 36 years later. Wilhelm Waiblinger, a young poet and admirer, left a poignant account of Hölderlin's day-to-day life during these long, empty years. Hölderlin continued to write poetry of a simplicity and formality quite unlike what he had been writing up to 1805. As time went on he became a kind of minor tourist attraction and was visited by curious travelers and autograph-hunters. Often he would play the piano or spontaneously write short verses for such visitors, confining himself to conventional subjects such as Greece, the Seasons, or The Spirit of the Times, pure in versification but almost empty of affect, although a few of these (such as the famous 'The Lines of Life', Die Linien des Lebens, which he wrote out for his carer Zimmer on a piece of wood) have a piercing beauty and have been set to music by many composers.

Hölderlin's own family did nothing to support him but instead petitioned (successfully) for his upkeep to be paid by the state. His mother and sister never visited him, and his stepbrother only once. His mother died in 1828: his sister and stepbrother quarrelled over the inheritance, arguing that too large a share had been allotted to Hölderlin, and tried unsuccessfully to have the will overturned in court. Neither of them attended his funeral, nor had the (now famous) friends of his childhood, Hegel and Schelling, had anything to do with him for years; the Zimmer family were his only mourners. His inheritance, including the patrimony left him by his father when he was two, had been kept from him by his mother and was untouched and continually accruing interest. He died a rich man, and never knew it.