Te Rata Mahuta was the fourth Māori king. When you google for him, you can find several pictures of him. The same is true for the three monarchs that succeeded him.
I am pretty sure that there are Wikimedians who have pictures in their personal albums of king Te Rata Mahuta and queen Te Atairangikaahu. It would be cool because at this time we do not have freely licensed illustrations for them.
When you consider the history of a country like New Zealand, the Māori are an integral and essential. It is important to have proper information and illustrations about the people and the culture of the Māori.
With material about subjects like the Māori in Wikidata and Commons basic information exists for a stub in any language. Check out for instance what we have about the first Māori king.