| Honorific-Prefix: | The Honourable |
| Ossie Mazengarb | |
| Office2: | Member of the New Zealand Legislative Council |
| Term Start2: | 22 June 1950 |
| Term End2: | 31 December 1950 |
| Birth Name: | Oswald Chettle Mazengarb |
| Birth Date: | 31 May 1890 |
| Birth Place: | Prahran, Victoria, Australia |
| Death Place: | Wellington, New Zealand |
| Profession: | Barrister |
Oswald Chettle Mazengarb (31 May 1890 – 27 November 1963), known as Ossie Mazengarb, was a New Zealand barrister.
Mazengarb was born in Prahran, a suburb of Melbourne, in 1890. His family moved to Dunedin soon after his birth and he received his education at Otago Boys' High School, which he attended from 1903 to 1905. From 1908 to 1911, he studied for a Bachelor of Arts at Otago University. A scholarship in political economy enabled him to study a further year and he graduated with a Master of Arts in 1912. He then moved to Wellington to study law at Victoria College and obtained a Bachelor of Laws in 1914 and a Master of Laws in 1917. He was a member of the debating club at both universities.
Mazengarb was admitted to the bar in 1914. He formed a partnership with John Barton in 1915. Barton was appointed magistrate in Gisborne and had to dissolve the partnership.[1] Mazengarb was joined by Ernst Peterson Hay and Robert Macalister and their practice soon rose to one of the largest in the capital city.
Mazengarb wrote a few legal textbooks. Aside from his legal and judicial careers, he was also a politician, standing for the United–Reform Coalition in the in the electorate,[2] and for National in the in the electorate.[3] He was appointed in 1950 as one of the so-called suicide squad in the Legislative Council to vote for its abolition.
Alongside Alfred North, Mazengarb was appointed King's Counsel on 18 April 1947.[4] [5] In the 1953 Coronation Honours, Mazengarb was appointed a Commander of the Order of the British Empire, for charitable and public services, especially in the field of law.
A well-known public appointment was in 1954, by the National government of the time, to chair the Special Committee on Moral Delinquency in Children and Adolescents, otherwise better known as the Mazengarb Report.
On 6 April 1920 at St John's Church in Invercargill, Mazengarb married Margaret Isabel Campbell. The couple had three daughters. Mazengarb died in Wellington on 27 November 1963.