Nigel Robert Merrett (born 1940) is a British zoologist and ichthyologist and former director of the fish section of the British Natural History Museum.
In 1998, Merrett participated in an expedition headed by Nikolas Vasilyevich Parin to collect deepwater specimens.
In 1997, Merrett, along with R.L. Haedrich, wrote the book Deep-Sea Demersal Fish and Fisheries. In the book, they warn against fishing in deep water.