Thomas Hobbes (/hɒbz/ HOBZ; 5 April 1588 – 4 December 1679) was an English philosopher, best known for his 1651 book Leviathan, in which he expounds an influential formulation of social contract theory. He is considered to be one of the founders of modern political philosophy.

In his early life, overshadowed by his father's departure following a fight, he was taken under the care of his wealthy uncle. Hobbes's academic journey began in Westport, leading him to the University of Oxford, where he was exposed to classical literature and mathematics. He then graduated from the University of Cambridge in 1608. He became a tutor to the Cavendish family, which connected him to intellectual circles and initiated his extensive travels across Europe. These experiences, including meetings with figures like Galileo, shaped his intellectual development.

After returning to England from France in 1637, Hobbes witnessed the destruction and brutality of the English Civil War from 1642 to 1651 between Parliamentarians and Royalists, which heavily influenced his advocacy for governance by an absolute sovereign in Leviathan, as the solution to human conflict and societal breakdown. Aside from social contract theory, Leviathan also popularized ideas such as the state of nature ("war of all against all") and laws of nature. His other major works include the trilogy De Cive (1642), De Corpore (1655), and De Homine (1658) as well as the posthumous work Behemoth (1681).

Hobbes contributed to a diverse array of fields, including history, jurisprudence, geometry, optics, theology, classical translations, ethics, as well as philosophy in general, marking him as a polymath. Despite controversies and challenges, including accusations of atheism and contentious debates with contemporaries, Hobbes's work profoundly influenced the understanding of political structure and human nature.

Thomas Hobbes was born on 5 April 1588 (Old Style), in Westport, now part of Malmesbury in Wiltshire, England. Having been born prematurely when his mother heard of the coming invasion of the Spanish Armada, Hobbes later reported that "my mother gave birth to twins: myself and fear." Hobbes had a brother, Edmund, about two years older, as well as a sister, Anne.

Although Thomas Hobbes's childhood is unknown to a large extent, as is his mother's name, it is known that Hobbes's father, Thomas Sr., was the vicar of both Charlton and Westport. Hobbes's father was uneducated, according to John Aubrey, Hobbes's biographer, and he "disesteemed learning." Thomas Sr. was involved in a fight with the local clergy outside his church, forcing him to leave London. As a result, the family was left in the care of Thomas Sr.'s older brother, Francis, a wealthy glove manufacturer with no family of his own.

Hobbes was educated at Westport church from age four, went to the Malmesbury school, and then to a private school kept by a young man named Robert Latimer, a graduate of the University of Oxford. Hobbes was a good pupil, and between 1601 and 1602 he went to Magdalen Hall, the predecessor to Hertford College, Oxford, where he was taught scholastic logic and mathematics. The principal, John Wilkinson, was a Puritan and had some influence on Hobbes. Before going up to Oxford, Hobbes translated Euripides' Medea from Greek into Latin verse.

At university, Thomas Hobbes appears to have followed his own curriculum as he was little attracted by the scholastic learning. Leaving Oxford, Hobbes completed his B.A. degree by incorporation at St John's College, Cambridge, in 1608. He was recommended by Sir James Hussey, his master at Magdalen, as tutor to William, the son of William Cavendish, Baron of Hardwick (and later Earl of Devonshire), and began a lifelong connection with that family. William Cavendish was elevated to the peerage on his father's death in 1626, holding it for two years before his death in 1628. His son, also William, likewise became the 3rd Earl of Devonshire. Hobbes served as a tutor and secretary to both men. The 1st Earl's younger brother, Charles Cavendish, had two sons who were patrons of Hobbes. The elder son, William Cavendish, later 1st Duke of Newcastle, was a leading supporter of Charles I during the Civil War in which he personally financed an army for the king, having been governor to the Prince of Wales, Charles James, Duke of Cornwall. It was to this William Cavendish that Hobbes dedicated his Elements of Law.