Thomas Beckwith FSA (10 February 1731 – 17 February 1786) was an English painter, genealogist and antiquary.

Beckwith was born at Rothwell, West Yorkshire, the son of a West Riding solicitor, and brother of Josiah Beckwith (b. 1734), attorney and antiquary. He was apprenticed as a house-painter to George Fleming of Wakefield, who tutored him in drawing and limning; subsequently Beckwith set himself up in business as a painter in York. He painted portraits and also made many drawings of antiques, local churches, ruins etc., some of which were finished in watercolour.^[1]

Beckwith acquired a great knowledge of heraldry and local family pedigrees which he amassed in 30–40 volumes of notes,^[2] seeming "to have spent much of his time in forming antiquarian and genealogical collections, of which he left a great mass behind him... they were so numerous that they have found their way into almost every collection of manuscripts which has been formed during the last half century."^[3] He was elected Fellow of the Society of Antiquaries of London, and also wrote a book on local history, "A Walk in and about the city of York", though it was not published.^[1]

In 1781 he took out a patent for "crayons for drawing and other purposes of various colours, superior to any hereforeto made."^[4] The new type of crayon, which could be sharpened like a pencil, was licensed to be manufactured and sold by the London artists' supplier George Riley.^[5]

Beckwith's wife, Frances, died on 29 August 1773, aged 36. Beckwith himself died in York on 17 February 1786. His son, Ray Beckwith (d. 19 Dec 1799), was a medical doctor who practised in York.^[2]

Thomas Beckwith's portrait was etched by William Doughty.^[6]