Ōtorohanga is a north King Country town in the Waikato region in the North Island of New Zealand. It is located south of Hamilton and north of Te Kūiti, on the Waipā River. It is a service town for the surrounding dairy-farming district. It is recognised as the "gateway" to the Waitomo Caves and as the "Kiwiana Town" of New Zealand. Until 2007, Ōtorohanga held a yearly 'Kiwiana Festival.'
Until the 1860s Ōtorohanga was a Ngāti Maniapoto village, with several whare (houses), peach trees and a flour mill. Huipūtea is a 300-year-old kahikatea tree, just to the south east of Ōtorohanga, which was the site of a skirmish in 1822 between Ngāti Maniapoto and Ngāpuhi. The village was abandoned after the invasion of the Waikato, except for Lewis Hettit's (or Hetet) farm. The area remained insecure, with Hettit's store being robbed by Te Kooti in 1869, but a meeting with Donald McLean later that year signalled moves towards peace.
John William Ellis became postmaster and opened a store in 1885 with Henry Valder and John Taonui Hetet. In 1886 Ngāti Maniopoto built a court room for the Native Land Court and from that year mail was delivered 3 times a month and disputes which had delayed development were settled. On 9 March 1887 the railway was extended from Te Awamutu and a 14-room hotel was built, primarily for those attending the Court. The sawmill, later run by Ellis and Burnand, started in 1890 and closed in 1912.
In the early 1900s many businesses were established by Māori, in particular John Ormsby (Hōne Ōmipi). The Otorohanga Times was formed in 1912; it merged with the King Country Chronicle to form the Waitomo News in 1980. McDonald’s began a limestone quarry south of Otorohanga in 1968, which was bought by Graymont in 2015.
Otorohanga’s population grew from 367 in 1916 to 1,569 in 1951, after which growth slowed. Although population dropped from 2,652 in 1991 and to 2,514 in 2013, the fall was much less than in the rest of King Country.
In 1986, the town briefly changed its name to "Harrodsville".