Tommaso Giordani (c.1730 – before 24 February 1806) was an Italian composer active in England and particularly in Ireland.
Giordani was born in Naples and came from a musical family. His father was Giuseppe Giordani senior who was born around 1695 in Naples, died after 1762, probably in London (no relation to the Neapolitan organist Carmine Giordani b. 1685). A younger brother was Giuseppe Giordani (1751–1798), called "Giordanello". Tommaso was trained in Naples and moved with the family to London around 1752. After three years at Covent Garden he brought out his first comic opera. In 1762 he appeared at the Theatre Royal, Haymarket as a singer. In 1764 he settled in Dublin. He was one of the leading musicians in the Irish capital from 1764 to 1781, when he returned to London. After two years he came back to Dublin, where he spent the remainder of his life. He had a stake in the short-lived "English Opera House", which he founded in 1783 and which produced works by Irish composers and librettists, also in a music shop, neither of which was financially successful.
Among his compositions are a number of operas, including Genius of Ireland (1784) and The Island of Saints, or The Institution of the Shamrock (1785), the oratorio Isaac (1767), and a large quantity of overtures, sonatas, concertos, quartets (mostly string quartets, though some with flute or keyboard), trios for violin, flute and basso continuo, songs, etc. He was organist of St Mary's Pro-Cathedral, Dublin, from 1784 to 1798, and conducted a Te Deum of his own at the celebration upon the recovery of King George III, 30 April 1789. Among his pupils were Lady Morgan, Thomas Simpson Cooke, and John Field, the inventor of the nocturne, who made his debut at one of Giordani's Rotunda concerts (4 April 1792). His last opera The Cottage Festival was produced at the Theatre Royal, Dublin, 28 Nov. 1796. Giordani composed in a tuneful, galant style and was often confronted with accusations of plagiarism. He died in Dublin.
On some musical scores the popular arietta Caro Mio Ben was ascribed to Giordanis younger brother Giuseppe Giordani, however after recent scholarship Tommaso Giordani is now attributed.