The dark-eyed junco is a species of junco, a group of small, grayish New World sparrows. The species is common across much of temperate North America and in summer it ranges far into the Arctic. It is a variable species, much like the related fox sparrow, and its systematics are still not completely resolved.

A junco, genus Junco, is a small North American bird in the New World sparrow family Passerellidae. Junco systematics are still confusing after decades of research, with various authors accepting between three and twelve species. Despite having a name that appears to derive from the Spanish term for the plant genus Juncus (rushes), these birds are seldom found among rush plants, which prefer wet ground, while juncos prefer dry soil.