Thomas Harrison (7 August (baptised) 1744 – 29 March 1829) was an English architect who flourished during the last two decades of the 18th century and the first three decades of the 19th century. Little is known of his early life, and his precise date of birth is uncertain. He was born in Richmond, North Yorkshire, and was baptised on 7 August 1744. In 1769 he was sent to study architecture in Rome. He began his professional career as an architect in 1782, following his success in a competition to design Skerton Bridge in Lancaster, Lancashire, after which he moved to Lancaster.

While living there, he carried out a number of projects, including a new tower and spire for St John's Church, a clock tower for the town hall, and new buildings within the complex of Lancaster Castle. During his work on Lancaster Castle, he was also involved in designing new buildings within Chester Castle, Cheshire. In 1795 Harrison moved with his family to Chester, where he spent the remainder of his career.

Following his success with Skerton Bridge, Harrison designed additional bridges, including Harrington Bridge in Derbyshire, St Mary's Bridge in Derby, Stramongate Bridge in Kendal, Cumbria, and smaller bridges in Lancashire and Cheshire.

Harrison is considered to have been a leader of Greek Revival architecture in the northwest of England. His major surviving works in this style include the Lyceum in Liverpool, the Portico Library in Manchester, and the Commercial Newsroom in Chester. Most of Harrison's works are in Lancashire and Cheshire, but he also designed buildings in North Wales, and in Shropshire. His only work away from this part of the country was his design for the New Buildings at Magdalen College, Oxford. In Chester, Harrison designed a house for himself, St Martin's Lodge. In addition to domestic and civic buildings, he worked on memorial structures, including the Jubilee Tower on Moel Famau in North Wales, Lord Hill's Column in Shrewsbury, Shropshire, and a memorial gateway in Holyhead, Anglesey. His final major designs were for two bridges in Chester. In 1825–26 he widened the Old Dee Bridge. He then designed a new bridge, the Grosvenor Bridge. This was not completed until after his death in 1829, but it was at the time the largest structure of its type in the world.

Key

Grade CriteriaI Buildings of exceptional interest.II* Particularly important buildings of more than special interest.II Buildings of special interest. Category (Scotland) CriteriaCategory A Buildings of national or international importance, either architectural or historic, or fine little-altered examples of some particular period, style or building type.Category B Buildings of regional or more than local importance, or major examples of some particular period, style or building type which may have been altered.Category C(S) Buildings of local importance, lesser examples of any period, style, or building type, as originally constructed or moderately altered; and simple traditional buildings which group well with others in categories A and B. "—" denotes a work that is not graded.

Works NameLocationPhotographDateNotesGradeOld Town HallLancaster, Lancashire1782Added the clock tower. Now Lancaster City Museum.St John's ChurchLancaster, Lancashire1783–84Added the west tower and spire.Skerton BridgeLancaster, Lancashire1783–1787A new bridge crossing the River Lune costing £14,000 (). It was the first large public bridge in England to have a flat road deck.Bridge HousesLancaster, Lancashire1786–87Built as a toll house and as houses for renting opposite Skerton Bridge.County GaolLancaster, Lancashire1788–1796Built within Lancaster Castle. Included the Keeper's House, the Female Felons' Prison, and the Male Felons' Prison.Harrington BridgeSawley, Derbyshire1789–90A new bridge over the River Trent to replace a ferry. It was severely damaged by a flood in 1904 and only small portions of it remains.St Mary's BridgeDerby, Derbyshire1789–1794Replacing a medieval bridge. It has a flat road deck carried on three arches.Chester CastleChester, Cheshire1789–1802The earliest building was the county gaol on a site sloping down to the River Dee. It has been largely demolished and was replaced by Cheshire County Hall. At about the same time the Shire Hall was built and still functions as a criminal court.Entrance screenChester Road, Wrexham, WalesAttributed to Harrison; an entrance screen to the now-demolished Acton Park.Springfield HallLancaster, Lancashire1790–1792A large suburban villa, almost certainly by Harrison. Demolished in 1862. The Centenary Building of the Royal Lancaster Infirmary now stands on the site. If by Harrison, it was his earliest house. Stramongate BridgeKendal, Cumbria1791–1797Rebuilding of a medieval bridge. It is a scheduled monument.