Kākāpō
Flightless birds are not new to us, as we have been introduced to ostriches even in our younger years. However, this does not make them less of a bird. Over time, as evolution goes by, they just lost the ability to fly. Other flightless birds include the steamer duck, weka, kiwi, takawahe, cassowary, penguin, and kākāpō.
The latter might be something you just see on Dr. Seuss movies, but they actually exist. Kākāpō, also known as owl parrot, is a species of large, flightless, nocturnal, ground-dwelling parrot of the super-family Strigopoidea, endemic to New Zealand. It has finely blotched yellow-green plumage, a distinct facial disc, a large grey beak, short legs, large feet, and relatively short wings and tail.