The tomtit (Petroica macrocephala) is a small passerine bird in the family Petroicidae, the Australasian robins.

The tomtit was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[3][4] Gmelin based his account on the "great-headed titmouse" that had been described and illustrated in 1783 by the English ornithologist John Latham in his book A General Synopsis of Birds.

The bird was seen at Queen Charlotte Sound on the north coast of New Zealand's South Island during James Cook's second voyage to the Pacific Ocean.

Banks owned a painting of the bird by Georg Forster who had accompanied Cook on the voyage.

[6][7] The tomtit is now placed with 13 other species in the genus Petroica that was introduced in 1829 by the English naturalist, William Swainson.

[8] The generic name combines the Ancient Greek petro- "rock" with oikos "home".

[9] The tomtit is one of four species of the genus Petroica found in New Zealand, the ancestors of which colonised from Australia.

[13] Either form has been used to describe a number of small birds, but in England tomtit was most commonly used as an alternate name of the blue tit.

The Snares subspecies feeds on the ground as well, in a similar fashion to the North or South Island robins.