Collapsible helmet

A collapsible helmet may include a number of chassis segments that are mechanically coupled to one another, where at least some of the chassis segments are collapsible into another chassis segment for storage, and where the chassis segments are expandable so that the helmet is suitable for wearing on a user's head for protection thereof. For example, certain aspects include a three-piece collapsible helmet that has interlocking fingers. In this manner, when the helmet is closed, the interlocking fingers allow the helmet to conveniently fold or collapse into a compact form. Moreover, when the helmet is opened, the interlocking fingers may provide a desired head coverage for protection of a wearer.