Thomas Jones (26 September 1742 – 29 April 1803) was a Welsh landscape painter. He was a pupil of Richard Wilson and was best known in his lifetime as a painter of Welsh and Italian landscapes in the style of his master. However, Jones's reputation grew in the 20th century when more unconventional works by him, not originally intended for exhibition, came to light. Most notable among these is a series of views of Naples which he painted from 1782 to 1783. By breaking with the conventions of classical landscape painting in favour of direct observation, they look forward to the work of Camille Corot and the Barbizon School in the 19th century. His autobiography, Memoirs of Thomas Jones of Penkerrig, went unpublished until 1951 but is now recognised as an important source of information on the 18th-century art world.
Thomas Jones was born in Trefonnen in Cefnllys, Radnorshire, the second of sixteen children to the landowner Thomas Jones of Trefonnen and his wife, Hannah. His formative years were spent on his father's estate at Pencerrig near Builth Wells; thus he is often referred to as Thomas Jones of Pencerrig to differentiate him from others of the same name. He was educated at Christ College, Brecon, and later at a school kept by Jenkin Jenkins at Llanfyllin in Montgomeryshire, before going to Oxford in 1759 to study at Jesus College. His university education was funded by a maternal uncle who, contrary to Jones's own wishes, hoped for him to enter the church. Jones dropped out of Oxford after this uncle’s death in 1761 and began to pursue his preferred career as an artist.
Jones moved to London and enrolled at William Shipley's drawing school in November 1761. Despite attending the life class at St Martin's Lane Academy, he remained unconfident of his ability to draw figures convincingly, and in 1763 he persuaded the leading landscape painter of the day (and fellow Welshman) Richard Wilson to take him on as a pupil. A high-spirited youth, Jones recorded in his journal that he and two rowdy fellow pupils were once rebuked by their master with the words, "Gentlemen, this is not the way to rival Claude".