The northern alligator lizard may have been named for its likeness to an alligator, but its habitat and smaller size belie the comparison. It is Canada's largest lizard, and can attain a total length of 25 cm (9.8 in.).

Most characteristic to all species of this family is its prominent longitudinal fold of skin on each side of the body. These allow for the expansion of the sides when the animal is feeding, breathing, or pregnant.

Its back is brown with irregular dark spots, and the sides are greyish.

Its tail will readily break off if grabbed, giving the animal a chance to escape. A replacement section will grow, and it is usually darker than the original.

This lizard is wary in the open and is usually found under cover of bark, logs, or stones. Insects and spiders are its main prey. It is live-bearing, producing litters of up to 15 young.

In Canada, it occurs in southern mainland British Columbia and Vancouver Island. In the U.S.A., it can be found in Washington, Oregon, Idaho and Montana. Its habitat is dry, often rocky, wooded or partly wooded areas, and sometimes grasslands.