In 2026, marketing agencies will face an identity project as marketplace shifts, fee pressures, and client demands compel them to fully relinquish their conventional role as client representatives. Agencies will diversify their offerings and roles — selling execution, managed services, proprietary products, and strategic partnerships. Restructuring and consolidation will lead to shedding headcount along with agency autonomy. Principal media, AI, M&A, and the creator economy will further reshape the role of the agency beyond being the “agent” of client strategy. Instead, agencies will become purveyors of marketing solutions. This report details Forrester’s predictions for marketing agencies in 2026.