The Bristoliinae is an extinct subfamily of trilobites, fossil marine arthropods, with species of small to average size.

Species belonging to this subfamily lived during the Botomian and Toyonian stage (Olenellus-zone), 522-513 million years ago, in the former continent of Laurentia, including what are today Mexico, the Appalachian Mountains and the south-western United States, and Canada (Northwest Territories).

The furrows that separate border, eye ridges, glabella and its lobes are distinct.

Fremontella halli is known from eastern Laurentia (Rome Formation, Alabama, USA).

All other species are known from western Laurentia: Lochmanolenellus mexicana from northern Mexico and South-East California, the species of Bristolia from southeastern California and southern Nevada, and an undescribed Bristolia-species from the North-West Territories, Canada.