Sir Nicholas John Hannen (24 August 1842 – 27 April 1900) was a British barrister, diplomat and judge who served in China and Japan.

He was the Chief Justice of the British Supreme Court for China and Japan from 1891 to 1900 and also served concurrently as Consul-General in Shanghai from 1891 to 1897.

[1] Hannen held the following appointments in China and Japan:[2] From 1871 to 1874 he was appointed Acting Assistant Judge of the British Supreme Court for China and Japan and was based in Yokohama,[3] period during which he assisted Oe Taku during the Maria Luz incident.

In 1878 he was appointed Crown Advocate of the Supreme Court, a position akin to that of a colonial attorney general.

[6] In 1891, on Rennie's retirement, he was appointed as Chief Justice of the British Supreme Court for China and Japan and Consul-General in Shanghai.

The opposition was not based on Hannen's ability but rather that it was inappropriate for one man to hold a judicial and executive position at the same time.

His death came just two weeks before his planned retirement and departure from Shanghai for the town of Wargrave, near Reading, Berkshire, where he owned a house, Lake Lodge.