Sir Arnold Henry Nordmeyer ONZ KCMG (born Heinrich Arnold Nordmeyer, 7 February 1901 – 2 February 1989) was a New Zealand politician and Presbyterian minister. As a member of Parliament (MP) he played a crucial role in the Labour Party, serving from 1935 to 1969. He served as minister of finance (1957–1960) and later as leader of the Labour Party and leader of the Opposition (1963–1965). Although he was a prominent statesman, Nordmeyer never ascended to the role of prime minister.

Despite facing backlash for the 1958 "Black Budget" as finance minister, his political legacy primarily revolves around his economic policies, especially his introduction of New Zealand's comprehensive national health service as minister of health (1941–1947).

Nordmeyer was born on 7 February 1901 in Dunedin, New Zealand. His father was a German immigrant, his mother was from Northern Ireland. He was educated at Waitaki Boys' High School, and at the University of Otago where he completed his BA. After graduating he studied theology, having always been highly religious. At university he became known for his skills in debating which were to serve him well in his later career. Although he did not join the Labour Party until 1933, he became increasingly sympathetic to the party's views. It was at this time that he met Walter Nash who may have been influential in shaping his views in health and social policy. In 1925 Nordmeyer received his ordination as a Presbyterian minister and was appointed to a position in the small town of Kurow.

While in Kurow during the Great Depression, Nordmeyer witnessed firsthand the effects of the economic downturn on the community and people of the town, which lead him to study radical political theory in pursuit of a solution. He also became interested in the welfare of workers involved in the construction of a hydroelectric dam on the Waitaki River. He became increasingly politically active as a result witnessing both the working conditions of the labourers and the poor living conditions of the unemployed men and their families who were attracted to the area by the promise of work. At Kurow, Nordmeyer, along with local doctor and future Labour MP Gervan McMillan and school headmaster Andrew Davidson developed ideas of how to apply Christian ethics to politics to solve the miseries of unemployment, poverty and illness – ideas that were later implemented by the First Labour Government of New Zealand. It was also in Kurow that Nordmeyer met his future wife, Frances Kernahan whom he married in 1931.

Shortly before the 1935 election Nordmeyer stepped down from his church position, stating an intent to contest the Oamaru seat for the Labour Party. He was elected. The 1935 election itself was a huge victory for Labour and the party's leader, Michael Joseph Savage, became the country's first Labour Prime Minister.

In Parliament Nordmeyer proved to be a skilled debater but also had a somewhat troubled relationship with his party's leadership. Nordmeyer became part of the faction led by John A. Lee who criticised Savage's policies as too moderate. Gradually, however, Nordmeyer became disillusioned with Lee, alleging that Lee was egotistical and self-important. Nordmeyer later co-operated with more moderate politicians such as Walter Nash in drafting the party's social security policies. He chaired both the caucus committee and the parliamentary select committee which considered the matters in more depth. Eventually the committees recommended a scheme containing a means-tested pension, universal superannuation, and free healthcare for hospital treatments, maternity care and general practitioner consultations all to be financed via direct taxation. At Nordmeyer's insistence, the health and pensions schemes would be combined into a single measure which later became the Social Security Act 1938.

After the 1938 election that Labour won resoundingly, tensions between the moderate and extreme wings of the party became worse. Nordmeyer attempted to take a position between both groups but was generally closer to Lee's camp than to the other. The year 1940 saw both the death of Savage and the expulsion from the Labour Party of Lee, a move which Nordmeyer opposed. He was one of the few speakers against the motion to expel Lee at the party conference that year, an action which would in later years give him a reputation for political courage. Nordmeyer nominated Gervan McMillan, an old friend from Kurow and a supporter of Lee, as the party's new leader. McMillan, however, was defeated by Peter Fraser, Savage's chief lieutenant.

In 1941 Nordmeyer became Minister of Health. In this role, which he held until 1947, he was responsible (along with Walter Nash) for introducing state subsidies for doctor's visits. The New Zealand Branch of the British Medical Association had disagreed with the government on the process of free general practitioner consultations where they refused to accept a state fee for their services. Doctors argued that the relationship between themselves and patients was dependent on a direct payment by the patient. A compromise was eventually reached where doctors would continue to charge patients directly after which time patients could then claim a social security rebate. With this initial hurdle overcome, Nordmeyer progressed with the governments agenda over the next six years introducing further benefits for pharmaceutical prescriptions, dental care, hospital outpatients and X-ray diagnosis.