Robert Thomas (November 1781 - 1 July 1860) was a newspaper proprietor, printer and early settler of South Australia.
In 1836, Thomas migrated to the new colony with his wife Mary and family on the Africaine, arriving at Holdfast Bay on 8 November. He printed Governor Hindmarsh's proclamation of the new colony (28 December 1836), and began printing copies of the South Australian Gazette and Colonial Register. By 1838, the Register was a weekly newspaper. Thomas also printed copies of the South Australian Church Hymn Book for the Rev. Charles Howard, the Royal South Australian Almanac (1838-1842) and from 1839, the Port Lincoln Herald and South Australian Commercial Advertiser.
The Register had a fierce policy of independence and this resulted in conflict with Governor George Gawler, who was often criticised for his economic policies. Gawler was particularly attacked in September 1840 over his ordering of the execution of two Ngarrindjeri men along the Coorong after the Maria shipwreck and the deaths of its passengers and crew. As a result, the Government ceased to use the services of Robert Thomas & Co. from 11 November 1840 - a loss to the company of ₤1650 a year.
After an unsuccessful trip to London to protest the lost of business from the Government, he returned to Adelaide, where he continued to be involved in further printing and publishing. He died on 1 July 1860 at his home in Hindley Street. His wife Mary was a poet and diarist, who published The Diary of Mary Thomas, which is considered a valuable history of her voyage on the Africaine and the early days of the colony.