This thesis explores the understudied phenomenon of anti-fandom culture in the digital age, focusing on how anti-fan communities targeting media figures manifest on social media platforms. By analysing online interactions and community dynamics, the research uncovers dimensions of negativity and toxicity, emphasising the toxic practices displayed by anti-fans. Additionally, the thesis examines parasocial interactions within anti-fandom culture, contributing to the understanding of parasocial dynamics on social media. Employing a qualitative research approach, the study uses content analysis with framing analysis to explore the complexities of anti-fandom culture online. Posts and comments from one anti-fan Facebook group were framed and analysed using a coding scheme, allowing for a detailed depiction of anti-fan culture formation. Findings reveal that anti-fans reinforce negativity through echo chambers on social media, where critical comments and toxic content fuel a cycle of dislike. Anti-fans voice grievances and construct a shared narrative of antipathy toward celebrities, often escalating into personal attacks or attempts to delegitimise their targets. Key practices include highlighting faults in media portrayals and spreading anti-fan creations. Anti-fans frame their negativity as justified criticism or holding celebrities to higher standards, highlighting the complex dynamics of anti-fandom in the digital age.