Sir John Edward Denniston (20 June 1845 – 22 July 1919) was a judge of the Supreme Court in Christchurch, New Zealand.

For some months he practised at Wanganui in partnership with George Hutchison, afterwards a prominent member of the House of Representatives.

In 1875, he became associated with Downie Stewart in Dunedin and the firm was subsequently joined by Allan Holmes, son of the Hon.

Court work was undertaken by Denniston, whose name was connected with most of the important civil and criminal cases in the province.

[5] Denniston was married on 15 November 1887, to Helen Mary, daughter of the Hon.