Thomas Allom (13 March 1804 - 21 August 1872) was an English artist, topographical illustrator and architect, and one of the founder members of what eventually became the Royal Institute of British Architects (RIBA).

He was born in Lambeth, south London, the son of a coachman from Suffolk. In 1819, he was apprenticed to architect Francis Goodwin for whom he worked until 1826. He then studied at the Royal Academy School. His designs for churches shown at exhibitions in 1824 and 1827 aroused considerable interest, and he later designed many buildings in London (including a workhouse in Marloes Road, Kensington (1847), the Church of Christ in Highbury in 1850, the Church of St Peter in Notting Hill in 1856, and the elegant Ladbroke Estate in west London). Further afield his works included workhouses at Calne, Wiltshire (1847) and in Liverpool, design of the William Brown Library also in Liverpool, (1857-1860), and the tower of the church of Basford St Leodegarius, near Nottingham (1860). He also worked with Sir Charles Barry on numerous projects, including the Houses of Parliament and the remodelling of Highclere Castle.

However, Allom is chiefly known for his numerous topographical works, which were used to illustrate books on travel. From the 1820s onwards, he travelled extensively through the UK and mainland Europe. In 1834 he arrived in Istanbul, Turkey, and produced hundreds of drawings during journeys through Anatolia, Syria and Palestine. The results of this expedition were published in 1838 in Constantinople and the Scenery of the Seven Churches of Asia Minor published in two volumes with text by Robert Walsh. Emily Reeve's Character and Costume in Turkey and Italy, published in London in 1840, was also illustrated with engravings by Allom. He is also remembered for numerous illustrations of China, published in China Illustrated in 1845.

Allom suffered from a heart condition in his later years, and although he only retired in 1870, his artistic and architectural output slowed during the 1860s. He designed Castelnau church in Barnes, west London, in 1868 – his local church to which he contributed £50 towards the cost of its construction – and in 1865 was commissioned to design a mausoleum for George Dodd in West Norwood Cemetery. Allom died aged 68 in Barnes, and was buried in Kensal Green Cemetery.

English architects