Thematic series were introduced to BJPsych Open by the current Editor-in-Chief to address key topics in psychiatry and mental health, specifically considering the impact on the global burden of diseases with associated treatments, outcomes, policy and research priorities. The increasing submission to BJPsych Open of articles about the psychosocial and mental health impacts of terrorism and collective violence naturally led to this thematic series. This paper introduces the journal’s series of published papers about terrorism and collective violence. While we identify the topics covered by the series and hope to generate conversation, this paper does not report a systematic review of the series. The thematic series consists of 13 articles; 9 were open submissions and 4 were commissioned. They include this review, an editorial concerning research methods and 11 papers reporting how people have responded to terrorist and violent incidents in 4 countries. Including this review, one paper was published in 2020, three in 2022, two in 2023, five in 2024 and two in 2025. The commissioned papers were added to broaden coverage of the Utøya attack on young people in Norway, and the shootings in Christchurch, New Zealand in 2019. Our intention was to enable the papers on these two incidents to sit alongside papers already submitted about them and the Manchester Arena bombing as well as articles about attacks in Germany. We begin by introducing the papers and comment in the discussion on a series of topics that we have selected as prominent in the series.