The Eurasian brown bear is one of the most common subspecies of the brown bear, and is found in much of Eurasia. It is also called the European brown bear, common brown bear, common bear, and colloquially by many other names. The genetic diversity of present-day brown bears has been extensively studied over the years and appears to be geographically structured into five main clades based upon analysis of the mtDNA.

The brown bear is a large bear species found across Eurasia and North America. It is one of the largest living terrestrial members of the order Carnivora, rivaled in size only by its closest relative, the polar bear, which is much less variable in size and slightly bigger on average. Adults of different subspecies range in weight from 80 to 600 kg, with males being heavier than females. Despite its name, brown bears aren't entirely brown; the pelage can be reddish to yellowish-brown, and dark brown to cream in color. During winter, brown bears in some populations hibernate and emerge during spring to regain up to 180 kg (400 lb) of weight. They have well developed dentition and claws, ideal for their lifestyle.