Mariano Guillén
Head of Brussels Office, based in Brussels
Mariano Guillén leads Leidar’s Brussels Office.
An experienced public policy and public affairs professional, Mariano brings extensive knowledge in government affairs across a range of sectors, including digital, technology, and energy. His deep understanding of EU policy and EU political landscape is an asset for helping Leidar’s clients navigate complex reputational and regulatory challenges.
In Brussels, he has successfully led numerous projects and multidisciplinary teams in the design and delivery of public affairs strategies and advocacy campaigns. He has driven impactful outcomes for global and European organizations, trade associations, and non-profits. Mariano also has significant expertise in trade association management and stakeholder engagement, working closely with EU institutions and international organizations—not only in Brussels but across other European capitals.
A Spanish national, Mariano has a background in law and international business management. He developed his career in the US and Spain before transitioning into EU affairs in Brussels. He is fluent in Spanish, English, and French.