The number of media representations of climate activists has increased dramatically in Sweden recently. Some climate actions have attracted particular attention from Swedish media, such as when activists stopped traffic and disrupted public events. In this article, I present an analysis of media representations of both supporters and critics of climate activists in terms of strategies of legitimisation and de-legitimisation. The study is based on an examination of 98 Swedish media texts. The results reveal that risk-taking, self-sacrificing, heroisation, normalisation and personification are legitimisation strategies, while de-legitimisation strategies involve de-politicisation, rigid opposition, undermining the motive and stigmatisation. A conclusion is that the identified (de)legitimisation strategies are an expression of and contribute to increased polarisation between those who support the activists and those who criticise them. This polarisation takes different forms (partisan polarisation, affective polarisation and cultural polarisation) and risks contributing to an antagonistic debate where political opponents are transformed into enemies to be destroyed.