According to Getty Art and Architecture Thesaurus, Protagonists are «in literary works or performing arts, the people or other characters who have the primary roles». For Turin 1911 project, Protagonists are people involved in conceiving, designing, building, documenting, and visiting the Fair.

Protagonists are in turn subdivided according to the general roles played in the Fair, and these roles include: artists (visual artists), committees, exhibitors, influencers, makers, performing artists, public figures, publishers, and writers (composers).

Finally, the specific roles played in the Turin 1911 Fair are identified. Artists can be craftspeople, filmmakers, illustrators, lithographers, painters (artists), photographers, and sculptors. Committees are divided into Exposition’s executive committee, Exposition’s general committee, individual pavilions' committee, and technical committee. Exhibitors are people who displayed their items at the Fair. Influencers are people who didn't take part in the Turin 1911 Fair but inspired protagonists of the Turin 1911. Makers are architects and engineers, builders, and designers. Performing artists comprise composers (people in music), conductors (musicians), instrumentalists, and singers. Publishers are companies who published documents od the Fair, like guidebooks and postcards. Public figures are subdivided according to the nation they belong to; currently, the distinction is limited to the Kingdom of Italy, Reign of Siam, and United Kingdom Of Great Britain And Northern Ireland, but it will be expanded. Writers are divided into journalists, novelists, and poets.