The Centre for the Study of Existential Risk is an interdisciplinary research centre within the University of Cambridge dedicated to the study and mitigation of risks that could lead to human extinction or civilisational collapse. We study existential risks, develop collaborative strategies to reduce them, and foster a global community of academics, technologists and policy-makers working to safeguard humanity. Our research focuses on biological risks, environmental risks, risks from artificial intelligence, and how to manage extreme technological risk in general. **Story** At the beginning of the twenty-first century Professor Lord Martin Rees, the Astronomer Royal and one of Cambridge's most distinguished scientists, offered humanity an uncomfortable message. Our century is special, because for the first time in 45 million centuries, one species holds the future of the planet in its hands – us. In 2012, together with Jaan Tallinn, the co-founder of Skype, and Huw Price, the Bertrand Russell Professor of Philosophy, they set out “to steer a small fraction of Cambridge's great intellectual resources, and of the reputation built on its past and present scientific pre-eminence, to the task of ensuring that our own species has a long-term future.” They were joined by an international advisory panel including academics like Stephen Hawking, and industry-leaders like Elon Musk. Since our first postdoctoral researchers started in September 2015, we have grown quickly.