Fascins are actin-binding proteins that cross-link filamentous actin into tightly packed parallel bundles. These bundles are important for the organization and morphology of an extremely diverse set of sub-cellular structures that include dynamic and stable cell-surface protrusions, stress fibres, and the specialized actin bundles of photoreceptor and stereocilia cells. In this review, we discuss the fascin gene family and its evolution, the actin-bundling activity of fascins and the molecular pathways by which it is regulated, and the role of the diverse actin/fascin structures in normal cellular processes. We discuss the mechanisms by which fascins contribute to disease pathologies, especially cancer, where fascin-1 is emerging as a novel therapeutic target in carcinoma metastasis. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.