Probably Graeme Hart. Not many Billionaires in NZ.
https://www.forbes.com/profile/graeme-hart/?list=rtb/&sh=13d986d5140d
Graeme Hart has multiple residences in New Zealand, including in Auckland, Queenstown,[16] and Waiheke Island. Hart also owns an island in Fiji, as well as two properties in Aspen, Colorado in the US.[17]
https://en.wikipedia.org/wiki/Graeme_Hart