Greta Thunberg’s meteoric rise from lonely school striker in August 2018 to global icon is one of the most remarkable political phenomena in recent decades, and one full of paradoxes. Thunberg started out with no resources, a child of 15 with limited experience and a history of Asperger’s. Thunberg’s iconic performance seems to have been able to turn these weaknesses into strengths. To understand how this happened, we must situate her analysis within the social media ecology. Two things distinguish this environment from previous phases: iconic protagonists now have wide degrees of control over their own performance, and audiences are no longer mere receptors of iconic performance, but active co-performers. Greta Thunberg is one of the first major political icons to have been fully formed within the new social media ecology. This article provides the first systematic analysis of this dynamic.