Waiau could refer to several places in New Zealand:
Settlements Waiau Pa, south of Auckland Waiau, Waikato, on the Coromandel Peninsula Waiau, Bay of Plenty, between Waihi and Waihi Beach Waiau, Taranaki Waiau, Canterbury Franz Josef / Waiau, on the West Coast near Franz Josef Glacier
Geographic features Waiau Bay Waiau River, Hawke's Bay Waiau River, Canterbury Waiau River, Southland Waiho River on the West Coast, formerly known as the Waiau River
Other New Zealand locations Waiau Branch, a Canterbury branch line railway in service from 1882 to 1978: see also Weka Pass Railway
Elsewhere Lake Waiau on Mauna Kea in Hawaii