The southern bog lemming is a small North American lemming. Its range overlaps with the other species in genus Synaptomys, the northern bog lemming, in southeastern Canada, but extends farther south.

A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae together with voles and muskrats, which form part of the superfamily Muroidea, which also includes rats, mice, hamsters, and gerbils. In popular culture, a longstanding myth holds that they exhibit herd mentality and jump off cliffs, committing mass suicide.