Thomas Andrew Knight (1759–1838), FRS, of Elton Hall in the parish of Elton in Herefordshire and later of Downton Castle, was a British horticulturalist and botanist. He served as the 2nd President of the Royal Horticultural Society (1811–1838).

The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity.