The only Garratt locomotives to ever operate in New Zealand were the three members of the class G delivered in 1928. They had been ordered due to rising train loads on the heavy grades on the North Island Main Trunk. By introducing such powerful locomotives, it was hoped to dispense with banking altogether.

They were designed as Double Pacifics and a special feature that distinguished them from other Garratts was the coal bunker that was located on an extension of the main frame behind the cab. This bunker was connected to a mechanical stoker. They also belonged to the few Garratts with three cylinders per bogie. While the outside cylinders were operated by Walschaerts valve gear, the inside ones were operated by these through a Gresley-Holcroft mechanism.

When it became obvious that these locomotives were too large and complicated for the requirements in New Zealand, it was decided to rebuild them into six Pacifics. The rebuilds were finished in 1937 and 1938 and featured a new centre cylinder to fit the smokebox that was now located above the cylinder. They came to the south island and were withdrawn in 1956.