Thomas Dundas, 2nd Earl of Zetland (5 February 1795 – 6 May 1873), was a British nobleman and politician.
Born in Marylebone, London, eldest son of the 1st Earl and his wife Harriet Hale, he was educated at Harrow and Trinity College, Cambridge. In 1818 he was elected Whig Member of Parliament for his father and grandfather's old seat of Richmond, becoming representative for York twelve years later. In 1835 he returned to Parliament as member for Richmond, and four years later succeeded his father as second Earl of Zetland.
Like his father a prominent freemason, Lord Zetland was the United Grand Lodge of England's Grand Master from 1844 to 1870. Zetland was a senior member of the Jockey Club and won The Derby and St Leger Stakes with his horse Voltigeur in 1850.
In the year of his succession to the earldom, he was appointed Lord Lieutenant and Custos Rotulorum of the North Riding of Yorkshire, and in 1861 became a Knight of the Thistle. He resigned the Order on being made a Knight Companion of the Garter in 1872, and died the following year at Aske Hall, Yorkshire.
He married, on 6 September 1823, Sophia Jane, daughter of Sir Hedworth Williamson, Bt. The union produced no issue and his titles passed to his nephew, Lawrence Dundas, who later became Marquess of Zetland.