Abstract: This paper aims to investigate the reciprocal relationship between VIAF® and Wikidata and their possible roles in the semantic web environment. It deals with their data, their approach, their domain, and their stakeholders, with particular attention to identification as a fundamental goal of Universal Bibliographic Control. After examining interrelationships among VIAF, Wikidata, libraries and other GLAM institutions, a double approach is used to compare VIAF and Wikidata: first, a quantitative analysis of VIAF and Wikidata data on personal entities, presented in eight tables; and second, a qualitative comparison of several general characteristics, such as purpose, scope, organizational and theoretical approach, data harvesting and management (shown in table 9). Quantitative data and qualitative comparison show that VIAF and Wikidata are quite different in their purpose, scope, organizational and theoretical approach, data harvesting, and management. The study highlights the reciprocal role of VIAF and Wikidata and its helpfulness in the worldwide bibliographical context and in the semantic web environment and outlines new perspectives for research and cooperation.