Isaac Newton Watt (1821–1886) was a soldier, merchant and a Member of Parliament in Taranaki, New Zealand in the mid-to-late 19th century.
He was born in London sometime in 1821, the son of Isaac Watt the land surveyor and Susanna Dunlop.
He studied medicine at St Bartholemew's Hospital in London, but ran out of money and could not complete the course.
With few prospects, the brothers-in-law, now friends, left London to start life afresh in New Zealand.
Through the early years of the 1850s Isaac Newton Watt came to be an influential and important man in the Province of New Plymouth.
The Taranaki Rifle Volunteer Corps had been founded late the last year, in response to growing settler concerns about Maori resistance to their land-buying approaches.