Co-CEO at Havas Media Group
As co-leader of a major global media agency group, Buffet influences how AdTech platforms are adopted and evaluated at massive scale, making him a significant figure in the ecosystem.
Last updated Apr 18, 2026 by jonholm
Guillaume Buffet serves as Co-CEO of Havas Media Group, overseeing one of the world's largest media buying and planning networks with significant programmatic and data-driven advertising capabilities. He has been instrumental in integrating AdTech platforms into agency workflows at scale.