Abstract: A modular helmet may be configured and operative to allow simple interchangeability of both a function and an appearance of the helmet, without the need for tools. In some embodiments, a modular helmet generally comprises a base, headgear configured and operative to secure the base to a wearer's head, and a removable protection portion configured and selectively operative to attach to the base without tools; accordingly, a function of the helmet is selectively altered in accordance with a characteristic of the protective portion attached to the base.