The black tailed goanna is a small but ubiquitous species of goanna found throughout Australia. It is secretive and agile species, spending much of its time in trees. It typically rests in tree hollows or under loose bark. It forages for insects and lizards, raids the nests of small birds, and every so often takes a small possum for dinner. Its conical, recurved teeth are adapted to gripping wriggly prey rather than slashing flesh like the steak-knife teeth of its larger relatives. It usually forages in trees, going from one tree to another within its range looking for food. Due to its warriness and fleetness of foot, it has been dubbed the racehorse goanna (possibly causing confusion with sand goannas which are sometimes called by the same name). The black tailed monitor is variably colored throughout its range, with some populations turning entriely black as adults, others turn black only on the head and tail, and others retain the light freckled appearance of juveniles all their lives.
Black tailed goannas are typically Tiny or Small sized but rare individuals can get Medium.