The Northern Flicker (Colaptes auratus) is a medium-sized member of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, the Cayman Islands, and is one of the few woodpecker species that migrate. There are over 100 common names for the Northern Flicker. Among them are: Yellowhammer, clape, gaffer woodpecker, harry-wicket, heigh-ho, wake-up, walk-up, wick-up, yarrup, and gawker bird. Many of these names are attempts at imitating some of its calls.

The Northern Flicker is part of the genus Colaptes which encompasses 12 New-World woodpeckers. There are two living and one extinct subspecies of C. auratus species. The existing sub-species were at one time considered separate species but they commonly interbreed where ranges overlap and are now considered one species by the American Ornithologists Union. Whether or not they are separate species is a well-known example of the species problem.

Adults are brown with black bars on the back and wings. A mid-to-large-sized woodpecker, it measures 28–36 cm (11–14 in) in length and 42–54 cm (17–21 in) in wingspan. The body mass can vary from 86 to 167 g (3.0 to 5.9 oz). Among standard scientific measurements, the wing bone measures 12.2–17.1 cm (4.8–6.7 in), the tail measures 7.5–11.5 cm (3.0–4.5 in), the bill measures 2.2–4.3 cm (0.87–1.7 in) and the tarsus measures 2.2–3.1 cm (0.87–1.2 in). The largest-bodied specimens are from the northern stretches of the species range, such as Alaska or Newfoundland and Labrador, whereas the smallest specimens come from Grand Cayman Island. A necklace-like black patch occupies the upper breast, while the lower breast and belly are beige with black spots. Males can be identified by a black or red moustachial stripe at the base of the beak. The tail is dark on top, transitioning to a white rump which is conspicuous in flight.