The concept of audience has continuously evolved alongside technological advancements, from mass media to social media, and now to AI-driven platforms. Traditional audience research relied on surveys and content analysis, but digital traces, algorithmic curation, and generative AI are redefining how we observe and understand audience behavior. This talk revisits the shifting landscape of audience studies, tracing its transformation through key technological milestones and the emergence of intelligent systems. I will discuss how AI and predictive analytics challenge established methods of measuring engagement, agency, and attention, while also introducing new opportunities for audience research. Ultimately, I pose a fundamental question: In an era where AI co-creates content and personalizes media consumption, who—or what—is the audience?