| Honorific-Suffix: | CBE OBE QC |
| Office: | Secretary-General of the International Commission of Jurists |
| Term Start: | 1970 |
| Term End: | 1990 |
| Predecessor: | Seán MacBride |
| Successor: | Adama Dieng |
| Office1: | Minister of State for Housing and Local Government |
| Primeminister1: | Harold Wilson |
| Term Start1: | 29 August 1967 |
| Term End1: | 28 September 1968 |
| Predecessor1: | Frederick Willey |
| Successor1: | Denis Howell |
| Office2: | Financial Secretary to the Treasury |
| Primeminister2: | Harold Wilson |
| Term Start2: | 21 October 1964 |
| Term End2: | 29 August 1967 |
| Predecessor2: | Alan Green |
| Successor2: | Harold Lever |
| Constituency Mp3: | Derby North |
| Term Start3: | 17 April 1962 |
| Term End3: | 29 May 1970 |
| Predecessor3: | Clifford Wilcock |
| Successor3: | Phillip Whitehead |
| Constituency Mp4: | Lewisham North |
| Term Start4: | 14 February 1957 |
| Term End4: | 18 September 1959 |
| Predecessor4: | Austin Hudson |
| Successor4: | Christopher Chataway |
| Birth Date: | 1916 9, df=yes |
| Birth Place: | Dublin, Ireland |
| Death Place: | Geneva, Switzerland |
| Party: | Labour (from 1956) |
| Spouse: | |
| Children: | 1 |
| Alma Mater: | Corpus Christi College, Cambridge |
Niall MacDermot CBE OBE QC (10 September 1916 – 22 February 1996) was a British Labour politician.
MacDermot was educated at Rugby School and Corpus Christi College, Cambridge, and served in the Intelligence Corps during the Second World War. He was first elected to the House of Commons as Member of Parliament (MP) for Lewisham North, at a by-election in 1957 following the death of Conservative MP Sir Austin Hudson.
MacDermot lost his seat two years later at the 1959 general election, and unsuccessfully contested the equivalent seat at the 1961 London County Council election. He returned to Parliament as MP for Derby North at a by-election in 1962.
He was Financial Secretary to the Treasury from 1964 to 1967, and retired from the Commons at the 1970 general election.
From 1970 to 1990, he was Secretary-General of the International Commission of Jurists, succeeding Seán MacBride.[1]
He was the grandson of Hugh Hyacinth O'Rorke MacDermot, who served as Solicitor General for Ireland in 1885 and 1886, and as Attorney General for Ireland in 1892. He was also the nephew of Frank MacDermot a Fine Gael politician.