| John Manchester Allen | |
| Parliament: | New Zealand |
| Constituency Mp: | Hauraki |
| Term Start: | 15 October 1938 |
| Term End: | 28 November 1941 |
| Predecessor: | Charles Robert Petrie |
| Successor: | Andy Sutherland |
| Birth Date: | 1901 8, df=yes |
| Birth Place: | Cheadle, Staffordshire, England |
| Death Place: | Libya |
| Death Cause: | Killed in action |
| Relatives: | Stephen Allen (uncle) William Allen (uncle) John Candlish (great-grandfather) |
| Branch: | New Zealand Military Forces |
| Serviceyears: | 1939–41 |
| Rank: | Lieutenant Colonel |
| Commands: | 21st Battalion |
| Battles: | Second World War |
| Mawards: | mentioned in despatches |
John Manchester Allen (3 August 1901 – 28 November 1941) was a New Zealand politician of the National Party. He also served in the Second World War and commanded the 21st Battalion from May 1941 until he was killed in action in Libya.
Allen was born in Cheadle, Staffordshire, England, in 1901. His father, John Candlish Allen, died in France in 1917 from wounds received in the First World War. His uncles were Stephen Allen and William Allen, and his grandfather was William Shepherd Allen. He was educated at King's College, Auckland, and at Pembroke College, Cambridge where he graduated with MA and LLB degrees. He was a farmer in Morrinsville, and an Anglican lay reader.
He represented the Hauraki electorate from to 1941, when he died. Following the outbreak of the Second World War, he volunteered to serve with the 2nd New Zealand Expeditionary Force and was posted to 18th Battalion as its second-in-command. He was in Crete[1] as commander of the 21st Battalion before being killed in action during an offensive in Libya. He was succeeded in the Hauraki electorate by Andy Sutherland, who won the resulting .