William Wordsworth (7 April 1770 – 23 April 1850) was a major English Romantic poet who, with Samuel Taylor Coleridge, helped to launch the Romantic Age in English literature with the 1798 joint publication Lyrical Ballads.

Wordsworth's magnum opus is generally considered to be The Prelude, a semiautobiographical poem of his early years which he revised and expanded a number of times. It was posthumously titled and published, prior to which it was generally known as the poem "to Coleridge." Wordsworth was Britain's Poet Laureate from 1843 until his death in 1850.

The second of five children born to John Wordsworth and Ann Cookson, William Wordsworth was born on 7 April 1770 in Wordsworth House in Cockermouth, Cumberland — part of the scenic region in northwest England, the Lake District. His sister, the poet and diarist Dorothy Wordsworth, to whom he was close all his life, was born the following year, and the two were baptised together. They had three other siblings: Richard, the eldest, who became a lawyer; John, born after Dorothy, who went to sea and died in 1805 when the ship of which he was Master, Earl of Abergavenny was wrecked off the south coast of England; and Christopher, the youngest, who entered the Church and rose to be Master of Trinity College, Cambridge. Their father was a legal representative of James Lowther, 1st Earl of Lonsdale and, through his connections, lived in a large mansion in the small town. Wordsworth, as with his siblings, had little involvement with their father, and they would be distant with him until his death in 1783.

Wordsworth's father, although rarely present, did teach him poetry, including that of Milton, Shakespeare and Spenser, in addition to allowing his son to rely on his own father's library. Along with spending time reading in Cockermouth, Wordsworth would also stay at his mother's parents house in Penrith, Cumberland. At Penrith, Wordsworth was exposed to the moors. Wordsworth could not get along with his grandparents and his uncle, and his hostile interactions with them distressed him to the point of contemplating suicide.

After the death of their mother, in 1778, John Wordsworth sent William to Hawkshead Grammar School in Lancashire and Dorothy to live with relatives in Yorkshire; she and William would not meet again for another nine years. Although Hawkshead was Wordsworth's first serious experience with education, he had been taught to read by his mother and had attended a tiny school of low quality in Cockermouth. After the Cockermouth school, he was sent to a school in Penrith for the children of upper class families and taught by Ann Birkett, a woman who insisted on instilling in her students traditions that included pursuing both scholarly and local activities, especially the festivals around Easter, May Day, and Shrove Tuesday. Wordsworth was taught both the Bible and the Spectator, but little else. It was at the school that Wordsworth was to meet the Hutchinsons, including Mary, who would be his future wife.

Wordsworth made his debut as a writer in 1787 when he published a sonnet in The European Magazine. That same year he began attending St John's College, Cambridge, and received his B.A. degree in 1791. He returned to Hawkshead for his first two summer holidays, and often spent later holidays on walking tours, visiting places famous for the beauty of their landscape. In 1790, he took a walking tour of Europe, during which he toured the Alps extensively, and visited nearby areas of France, Switzerland, and Italy.

In November 1791, Wordsworth visited Revolutionary France and became enthralled with the Republican movement. He fell in love with a French woman, Annette Vallon, who in 1792 gave birth to their child, Caroline. Because of lack of money and Britain's tensions with France, he returned alone to England the next year. The circumstances of his return and his subsequent behaviour raise doubts as to his declared wish to marry Annette, but he supported her and his daughter as best he could in later life. In 1802, he visited Calais with his sister Dorothy and met Annette and his daughter Caroline. The purpose of the visit was to pave the way for his forthcoming marriage to Mary Hutchinson. Afterwards he wrote the poem "It is a beauteous evening, calm and free," recalling his seaside walk with his daughter, whom he had not seen for ten years. At the conception of this poem, he had never seen his daughter before. The occurring lines reveal his deep love for both child and mother. The Reign of Terror estranged him from the Republican movement, and war between France and Britain prevented him from seeing Annette and Caroline again for several years. There are strong suggestions that Wordsworth may have been depressed and emotionally unsettled in the mid-1790s.

With the Peace of Amiens again allowing travel to France, in 1802 Wordsworth and his sister, Dorothy, visited Annette and Caroline in France and arrived at a mutually agreeable settlement regarding Wordsworth's obligations.

In his "Preface to Lyrical Ballads", which is called the "manifesto" of English Romantic criticism, Wordsworth calls his poems "experimental." The year 1793 saw Wordsworth's first published poetry with the collections An Evening Walk and Descriptive Sketches. He received a legacy of £900 from Raisley Calvert in 1795 so that he could pursue writing poetry. That year, he met Samuel Taylor Coleridge in Somerset. The two poets quickly developed a close friendship. In 1797, Wordsworth and his sister Dorothy moved to Alfoxton House, Somerset, just a few miles away from Coleridge's home in Nether Stowey. Together, Wordsworth and Coleridge (with insights from Dorothy) produced Lyrical Ballads (1798), an important work in the English Romantic movement. The volume gave neither Wordsworth's nor Coleridge's name as author. One of Wordsworth's most famous poems, "Tintern Abbey", was published in the work, along with Coleridge's "The Rime of the Ancient Mariner". The second edition, published in 1800, had only Wordsworth listed as the author, and included a preface to the poems, which was augmented significantly in the 1802 edition. This Preface to Lyrical Ballads is considered a central work of Romantic literary theory. In it, Wordsworth discusses what he sees as the elements of a new type of poetry, one based on the "real language of men" and which avoids the poetic diction of much eighteenth century poetry. Here, Wordsworth gives his famous definition of poetry as "the spontaneous overflow of powerful feelings: it takes its origin from emotion recollected in tranquility." A fourth and final edition of Lyrical Ballads was published in 1805.

Wordsworth, Dorothy and Coleridge traveled to Germany in the autumn of 1798. While Coleridge was intellectually stimulated by the trip, its main effect on Wordsworth was to produce homesickness. During the harsh winter of 1798 – 99, Wordsworth lived with Dorothy in Goslar, and, despite extreme stress and loneliness, he began work on an autobiographical piece later titled The Prelude. He wrote a number of famous poems, including "The Lucy poems". He and his sister moved back to England, now to Dove Cottage in Grasmere in the Lake District, and this time with fellow poet Robert Southey nearby. Wordsworth, Coleridge and Southey came to be known as the "Lake Poets". Through this period, many of his poems revolve around themes of death, endurance, separation and grief.

In 1802, after Wordsworth's return from his trip to France with Dorothy to visit Annette and Caroline, Lowther's heir, William Lowther, 1st Earl of Lonsdale, paid the ₤4,000 debt owed to Wordsworth's father incurred through Lowther's failure to pay his aide. Later that year, Wordsworth married a childhood friend, Mary Hutchinson. Dorothy continued to live with the couple and grew close to Mary. The following year, Mary gave birth to the first of five children, three of whom predeceased William and Mary.

Wordsworth had for years been making plans to write a long philosophical poem in three parts, which he intended to call The Recluse. He had in 1798 – 99 started an autobiographical poem, which he never named but called the "poem to Coleridge", which would serve as an appendix to The Recluse. In 1804, he began expanding this autobiographical work, having decided to make it a prologue rather than an appendix to the larger work he planned. By 1805, he had completed it, but refused to publish such a personal work until he had completed the whole of The Recluse. The death of his brother, John, in 1805 affected him strongly.

The source of Wordsworth's philosophical allegiances as articulated in The Prelude and in such shorter works as "Lines composed a few miles above Tintern Abbey" has been the source of much critical debate. While it had long been supposed that Wordsworth relied chiefly on Coleridge for philosophical guidance, more recent scholarship has suggested that Wordsworth's ideas may have been formed years before he and Coleridge became friends in the mid 1790s. While in Revolutionary Paris in 1792, the twenty-two year old Wordsworth made the acquaintance of the mysterious traveller John "Walking" Stewart (1747 – 1822), who was nearing the end of a thirty years' peregrination from Madras, India, through Persia and Arabia, across Africa and all of Europe, and up through the fledgling United States. By the time of their association, Stewart had published an ambitious work of original materialist philosophy entitled The Apocalypse of Nature (London, 1791), to which many of Wordsworth's philosophical sentiments are likely indebted.

In 1807, his Poems in Two Volumes were published, including "Ode: Intimations of Immortality from Recollections of Early Childhood". Up to this point Wordsworth was known publicly only for Lyrical Ballads, and he hoped this collection would cement his reputation. Its reception was lukewarm, however. For a time (starting in 1810), Wordsworth and Coleridge were estranged over the latter's opium addiction. Two of his children, Thomas and Catherine, died in 1812. The following year, he received an appointment as Distributor of Stamps for Westmorland, and the £400 per year income from the post made him financially secure. His family, including Dorothy, moved to Rydal Mount, Ambleside (between Grasmere and Rydal Water) in 1813, where he spent the rest of his life.

In 1814 he published The Excursion as the second part of the three-part The Recluse. He had not completed the first and third parts, and never would. He did, however, write a poetic Prospectus to "The Recluse" in which he lays out the structure and intent of the poem. The Prospectus contains some of Wordsworth's most famous lines on the relation between the human mind and nature:

My voice proclaims

How exquisitely the individual Mind

(And the progressive powers perhaps no less

Of the whole species) to the external World

Is fitted:--and how exquisitely, too,

Theme this but little heard of among Men,

The external World is fitted to the Mind.

Some modern critics recognize a decline in his works beginning around the mid-1810s. But this decline was perhaps more a change in his lifestyle and beliefs, since most of the issues that characterize his early poetry (loss, death, endurance, separation and abandonment) were resolved in his writings. But, by 1820, he enjoyed the success accompanying a reversal in the contemporary critical opinion of his earlier works. Following the death of his friend the painter William Green in 1823, Wordsworth mended relations with Coleridge. The two were fully reconciled by 1828, when they toured the Rhineland together. Dorothy suffered from a severe illness in 1829 that rendered her an invalid for the remainder of her life. In 1835, Wordsworth gave Annette and Caroline the money they needed for support.

Wordsworth received an honorary Doctor of Civil Law degree in 1838 from Durham University, and the same honor from Oxford University the next year. In 1842 the government awarded him a civil list pension amounting to £300 a year. With the death in 1843 of Robert Southey, Wordsworth became the Poet Laureate. He initially refused the honour, saying he was too old, but accepted when Prime Minister Robert Peel assured him "you shall have nothing required of you" (he became the only laureate to write no official poetry). When his daughter, Dora, died in 1847, his production of poetry came to a standstill.

William Wordsworth died by re-aggravating a case of pleurisy on 23 April 1850, and was buried at St. Oswald's church in Grasmere. His widow Mary published his lengthy autobiographical "poem to Coleridge" as The Prelude several months after his death. Though this failed to arouse great interest in 1850, it has since come to be recognized as his masterpiece.