Sir Ernest Marsden CMG CBE MC FRS (19 February 1889 – 15 December 1970) was an English-New Zealand physicist.

[6] In 1915 he moved to Victoria University College in Wellington, New Zealand, to replace Thomas Laby as Professor of Physics; Rutherford recommended his appointment there.

Marsden served in France during World War I as a Royal Engineer in a special sound-ranging section and was awarded the Military Cross in the 1919 King's Birthday Honours.

He was appointed Assistant Director of Education before accepting the position of Secretary of New Zealand's new Department of Scientific and Industrial Research (DSIR) in 1926.

While this vision was not fully realised, in 1946 he established a team of scientists to carry out research into atomic energy and the application of nuclear science to problems in agriculture, health, and industry.

[8] Marsden retired in 1954 and returned to Wellington, where he continued to work and travel extensively, serving on a number of committees and conducting research into environmental radioactivity.

In 1966, the same year France began testing nuclear bombs in the Pacific, Marsden suffered a stroke which left him confined to a wheelchair.