William Henry Fox Talbot (11 February 1800 – 17 September 1877) was the inventor of calotype process, the precursor to most photographic processes of the 19th and 20th centuries. He was also a noted photographer who made major contributions to the development of photography as an artistic medium. His work in the 1850s on photo-mechanical reproduction led to the creation of the photoglyphic engraving process, the precursor to photogravure. Talbot is also remembered as the holder of a patent which, some say, affected the early development of commercial photography in Britain. Additionally, he made some important early photographs of Oxford, Paris, and York.

Talbot was known by his second name Henry, rather than William. Fox came from his mother's maiden name and was not passed on to his children. Although he signed his name as H.F. Talbot as well as H. Fox Talbot, he was most often referred to by his contemporaries as 'Mr Fox Talbot' or 'Mr H Fox Talbot', including by his mother. 'H Fox Talbot' was also the style he chose for his most important publications, including The Pencil of Nature.

Talbot was the only child of William Davenport Talbot, of Lacock Abbey, near Chippenham, Wiltshire, and of Lady Elisabeth Fox Strangways, daughter of the 2nd Earl of Ilchester. Talbot was educated at Rottingdean, Harrow and at Trinity College, Cambridge, where he was awarded the Porson prize in Classics in 1820, and graduated as twelfth wrangler in 1821. From 1822 to 1872, he frequently communicated papers to the Royal Society, many of them on mathematical subjects. At an early period, he had begun his optical researches, which were to have such important results in connection with photography. To the Edinburgh Journal of Science in 1826 he contributed a paper on "Some Experiments on Coloured Flame"; to the Quarterly Journal of Science in 1827 a paper on "Monochromatic Light"; and to the Philosophical Magazine a number of papers on chemical subjects, including one on "Chemical Changes of Colour." Talbot engaged in photographic experiments beginning in early 1834, well before 1839, when Louis Daguerre exhibited his pictures taken by the sun. After Daguerre's discovery was announced (without details), Talbot showed his four-year old pictures at the Royal Institution on 25 January 1839. Within a fortnight, he freely communicated the technical details of his photogenic drawing process to the Royal Society. Daguerre would not reveal the manipulatory details of his process until August. In 1841, Talbot announced his discovery of the calotype, or talbotype, process. This process reflected the work of many predecessors, most notably John Herschel and Thomas Wedgwood. In August 1841, Talbot licensed Henry Collen, the miniature painter (1798-c1872) as the first professional calotypist. Talbot's original contributions included the concept of a negative from which many positive prints can be made (although the terms negative and positive were coined by Herschel), and the use of gallic acid for developing the latent image. In 1842, for his photographic discoveries, which are detailed in his The Pencil of Nature (1844), he received the Rumford Medal of the Royal Society.

In February 1841, Talbot obtained a patent for the calotype process. At first, he was selling individual patent licences for £20 each, but later he lowered the fee to £4 and waived the payment for those who wished to use the process only as amateurs. Professional photographers, however, had to pay up to £300 annually. In a business climate where many patent holders were attacked for enforcing their rights, Talbot's behaviour was widely criticized, especially after 1851 when Frederick Scott Archer publicized the collodion process he had invented. Talbot declared that anyone using Archer's process would still be liable to get a license from Talbot for calotype (Archer himself never obtained a patent for collodion). One reason Talbot patented the calotype was that he had spent many thousands of pounds (then a fortune) on the development of the calotype process over several years. It is also significant that, although the daguerreotype process was supposed to be free to the world, Daguerre secured a British patent on his own process making it illegal for people in Britain to practice his process without a license. The purpose behind this patenting in Britain is not clear, but perhaps it was to stop Talbot from claiming priority or developing his system against Daguerre. Talbot's negative/positive process eventually succeeded as the basis for almost all 19th and 20th century photography. The daguerreotype, although stunningly beautiful, was rarely used by photographers after 1860, and had died as a commercial process by 1865. One person who tried to use the daguerreotype as a method of reproduction without Talbot's process was the English soldier, geologist, inventor and photographer Levett Landon Boscawen Ibbetson. But as good as Ibbetson's attempts were at producing something like a lithograph from the original daguerrotype, the end result could not compete with Talbot's process. They were simply too expensive. Ibbetson began experimenting with Talbot's calotype, and in 1842 wrote to Talbot "I have been going on with experiments in the Callotype & have had some very good results as to depth of Colour." By 1852, Capt. Ibbetson was showing his book using the Talbot calotype process, called "Le Premier Livre Imprimè par le Soleil" at a London Society of Arts exhibition.

The calotype was a refinement of his earlier photogenic drawing process in the use of a developing agent (gallic acid and silver nitrate) to bring out a latent negative image on the exposed paper. The negative meant that the print could be reproduced as many times as was required. The daguerreotype was a direct positive process and not reproducible, just as a Polaroid colour photograph where a copy has to be made. On the other hand, the calotype, despite waxing of the negative paper to make the image clearer, still was not pin sharp like the metallic daguerreotype as the paper fibres degraded the image produced. The problem was resolved in 1851 (the year of Daguerre's death) when the wet collodion process enabled glass to be used as a support, the lack of detail often found in calotype negatives was removed and pin sharp images, similar in detail to the daguerreotype were created. The wet collodion negative not only brought about the end of the calotype in commercial use, but also spelled the end of the daguerreotype as a common process for portraiture.

In August 1852, The Times published an open letter by Lord Rosse, the President of the Royal Society, and Charles Lock Eastlake, the president of the Royal Academy, who called on Talbot to relieve his patent pressure that was perceived as stifling the development of photography. In his response, Talbot agreed to waive licensing fees for amateurs, but he continued to pursue professional portrait photographers, having filed several lawsuits. The cost of the license for anyone wishing to make portraits for sale was £100 for the first year and £150 each subsequent year. In 1854, Talbot applied for an extension of the 14-year patent, to be expired in 1855. At that time one of his lawsuits, against a photographer Martin Laroche, was heard by the court. The Talbot v. Laroche case was the pivotal point of the story. Laroche's side argued that the patent was invalid, as a similar process was invented earlier by Joseph Reade, and that using the collodion process does not infringe the calotype patent anyway because of significant differences between the two processes. In the verdict, the jury upheld the calotype patent but agreed that Laroche was not infringing upon it by using the collodion process. Disappointed by the outcome, Talbot chose not to extend his patent.

Talbot was active in politics, being a moderate Reformer who generally supported the Whig Ministers. He served as Member of Parliament for Chippenham between 1832 and 1835 when he retired from Parliament. He also held the office of High Sheriff of Wiltshirein 1840.

Whilst engaged in his scientific researches, he devoted much time to archaeology. He published Hermes, or Classical and Antiquarian Researches (1838-39), and Illustrations of the Antiquity of the Book of Genesis (1839). With Sir Henry Rawlinson and Dr Edward Hincks he shares the honour of having been one of the first decipherers of the cuneiform inscriptions of Nineveh. He was also the author of English Etymologies (1846).

In 1843-44, he set up an establishment in Baker Street, Reading, for the purpose of mass producing salted paper prints from his calotype negatives. The Reading Establishment (as it was known) also produced prints from other calotypist’s negatives and even produced portraits and copy prints at the studio.

He died in Lacock Abbey village and is buried along with his wife and children in the churchyard there.