Lieutenant-Colonel Sir Richard Henry Bonnycastle (30 September 1791 - 3 November 1847) was an officer of the British army active in Upper Canada. He studied at the Royal Military Academy, Woolwich, as a cadet, and passed out as a second lieutenant of the royal engineers 28 September 1808, becoming a first lieutenant in the following year. He served at the siege of Flushing in 1809, and in the American campaigns of 1812-14, during which he was present at the capture of Fort Castine, and the occupation of the part of the state of Maine east of the Penobscot, and was commanding engineer at the construction of the extensive works thrown up by the British on the Castine peninsula. He attained the rank of captain in 1814. he served with the army of occupation in France.