The New Zealand fernbird or simply fernbird (Poodytes punctatus) is an insectivorous bird endemic to New Zealand. In the Māori language, it is named kōtātā or mātātā.

The New Zealand fernbird, Poodytes punctatus, was described by the French zoologists Jean Quoy and Joseph Gaimard in 1832 from a specimen collected in Tasman Bay / Te Tai-o-Aorere, South Island, New Zealand. They coined the binomial name, Synallaxis punctata.

In the past, this species had the binomial names Bowdleria punctatus, and more recently, Megalurus punctatus. Recent moluecular phylogenetic studies of the grassbird family Locustellidae have shown that the genus Megalurus was not monophyletic, resulting in the New Zealand fernbird, and four other Australasian species, now considered to be in the genus Poodytes.

There are five subspecies of New Zealand fernbird present on different islands. They differ in extent of reddish-brown and intensity of streaking, as well as size:

The related Chatham fernbird (Poodytes rufescens), which became extinct around 1900, was sometimes treated as a subspecies of this species.

The adult has a brown plumage streaked in black. The head, the upperparts and the brown wings are streaked blackish. The long graduated tail is a duller brown, with the rectrices darker. On the underparts, the chin, throat, breast and abdomen are whitish, finely mottled and also streaked blackish on the breast. The flanks, the sides of the chest and the subcaudal covers are brown and streaked blackish, more clearly on the flanks. On the head, the forehead and cap are brown.

The presence of a whitish eyebrow may be more or less clear. The auricular coverts are grey-brown with darker fine streaks that blend into the brown of the upperparts on the sides of the neck.

The beak is blackish, with the lower mandible more gray. The eyes are dark brown. Legs and toes are pinkish-brown. Both sexes are similar and the juvenile also looks like the adults.