Sir Thomas Deane (Cork, 1792 – Dublin, 1871) was an Irish architect. He was the father of Sir Thomas Newenham Deane, and grandfather of Sir Thomas Manly Deane, who were also architects.
Thomas was born in Cork, the eldest son of Alexander Deane, a builder, and Elizabeth Sharpe. His grandparents and uncle were also builders and architects, and had married into families of the same professions, the Kearns and Hargraves.
His father died in 1806, leaving his mother with seven children to bring up. There was a flaw in his will, which prevented Mrs. Deane from acquiring the properties that he owned in Cork city, and a private act of parliament was required to enable her to gain the leases of the properties. Mrs. Deane continued the family business, and Thomas started work there at fourteen years of age. In 1811 he designed his first building, the Cork Commercial Buildings, on South Mall, won in competition against William Wilkins (1778-1839).
Deane was to the forefront of the development of the arts and sciences in his native city. He served on Cork Corporation for many years. He was Mayor of Cork in 1815, 1830 and 1851, and was knighted in 1830. He was a staunch Tory, but ended up supporting a Catholic, Daniel Callaghan, in 1830. Later in life he grew tired of the political in-fighting.
In 1820 he bought the Ummera Estate in County Cork, and later bought and renovated a Georgian house at Dundanion close to Blackrock.
He designed a number of buildings in the city of Cork, including parts of the University College campus, and St Mary's Cathedral, Tuam (completed after his death, in 1878).
In 1860 he moved to Dublin, buying a house in Longford Terrace in Monkstown. He was elected President of the Royal Hibernian Academy in 1866.