| Honorific Prefix: | Sir |
| Robert O'Callaghan | |
| Birth Date: | October 1777 |
| Death Place: | Clarges Street, London |
| Allegiance: | United Kingdom |
| Branch: | British Army |
| Serviceyears: | 1794–1840 |
| Rank: | Lieutenant-General |
| Commands: | 39th Regiment of Foot 3rd Brigade, 2nd Division 13th Brigade, 7th Division 3rd Brigade, AOOF 7th Brigade, AOOF Scotland Command Madras Army |
| Battles: | |
| Awards: | Army Gold Cross with two clasps |
| Relations: | Cornelius O'Callaghan, 1st Baron Lismore (father) Frances Ponsonby (mother) Sir William Ponsonby (cousin) |
Lieutenant-General Sir Robert William O'Callaghan (October 1777 – 9 June 1840) was a British Army officer and politician.
Born the son of Cornelius O'Callaghan, 1st Baron Lismore, O'Callaghan was commissioned into the 128th Regiment of Foot in 1794.[1] He served in the Peninsular War and temporarily commanded a brigade within the 2nd Division between January and July 1813 and permanently commanded a brigade of the 2nd Division between February and April 1814.[1] He went on to command the 13th Brigade in France in 1815, the 3rd Brigade between 1815 and 1817 and the 7th Brigade in 1818.[1] He served with the Army of Occupation in France and then became Commander-in-Chief, Scotland in 1825 and Commander-in-Chief of the Madras Army in 1831 before retiring in 1836.[1]
He sat in the Irish House of Commons as the Member of Parliament for Bandonbridge from 1798 to 1800.[1]
He was also colonel of the 97th Regiment of Foot and then of the 39th Regiment of Foot.[1] He died unmarried in London.
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