| Honorific Prefix: | The Right Honourable |
| Sir Barnes Peacock | |
| Birth Name: | George Barnes Peacock |
| Birth Date: | 1 July 1805 |
| Birth Place: | Middlesex, England |
| Death Place: | South Kensington, London, England |
| Children: | 11 (including Walter) |
| Nationality: |
|
| Occupation: | lawyer, judge |
| Office: | Chief Justice of Calcutta High Court |
| Term: | 1 July 1862 - 1870 |
| Predecessor: | Position Established |
| Successor: | Sir Richard Couch |
| Office2: | Chief Justice of the Supreme Court of Judicature at Fort William |
| Term2: | 1859 - 1862 |
| Predecessor2: | Sir James Colvile |
| Successor2: | Position Abolished |
Sir George Barnes Peacock (1 July 1805 – 3 December 1890) was an English barrister and judge who served as the first Chief Justice of the Calcutta High Court in India and the final Chief Justice of the Supreme Court of Judicature at Fort William.
Peacock was the son of Lewis Peacock, a solicitor. After practising as a special pleader, he was called to the bar in 1836 by the Inner Temple, and joined the Home Circuit. In 1844, he obtained great reputation by pointing out the flaw which invalidated the conviction of Daniel O'Connell and his fellow defendants. He took silk in 1850, and was elected a bencher of the Inner Temple the same year.
In 1852, Peacock went to India as a legal member of the Governor General's Council. The Legislative Council was established soon after his arrival, and although no orator, he was so frequent a speaker that legislation enjoining councillors to deliver their speeches sitting was said to have been devised with the sole object of restraining him. As a member of Lord Dalhousie's council, he supported the annexation of Oudh, and he stood by Lord Canning all through the Indian Mutiny.
In 1859, Peacock became the last Chief Justice of the Supreme Court of Judicature at Fort William, and was knighted. He was appointed the first Chief Justice of the Calcutta High Court on 1 July 1862. He returned to England in 1870 and in 1872 was appointed a paid member of the Judicial Committee of the Privy Council, the court of last resort for the British Empire.