Wiremu Hau was a rangatira (chief) at Waimate in the Bay of Islands. He signed the Treaty of Waitangi on 6 February 1840 at Waitangi.
Hau was baptised in the early 1830s. On 13 July 1844 he wrote to chiefs inviting them to Waimate to discuss the behaviour of Ngāpuhi chief Hōne Heke Pōkai, whose men had recently looted Kororāreka and cut down the flagstaff on Maiki Hill. During the subsequent Northern War, Hau fought alongside the British at Ōhaeawai in July 1845.
Hau attended the 1860 conference of Māori leaders at Kohimarama organised by Governor Thomas Gore Browne. In 1863 he sent a letter to Governor George Grey asserting that Ngāpuhi had no interest in the fighting in Waikato and Taranaki. He later became an assessor in the Native Land Court.
In 1874 Hau and his son Hamiora were two of the leading chiefs present when the superintendent of Auckland province visited Mangōnui. According to a newspaper report, Hau was believed to be one of the oldest chiefs in New Zealand at this time.