The global catastrophic risk (GCR) and existential risk (ER) literature focuses on analyzing and preventing potential major global catastrophes including a human extinction event. Over the past two decades, the field of GCR/ER research has grown considerably. However, there has been little meta-research on the field itself. How large has this body of literature become? What topics does it cover? Which fields does it interact with? What challenges does it face? To answer these questions, here we present the first systematic bibliometric analysis of the GCR/ER literature. We consider all 3437 documents in the OpenAlex database that mention either GCR or ER and use bibliographic coupling (two documents are considered similar when they share many references) to identify 10 distinct emergent research clusters in the GCR/ER literature. These clusters align in part with commonly identified drivers of GCR, such as advanced artificial intelligence (AI), climate change, and pandemics or discuss the conceptual foundations of the GCR/ER field. However, the field is much broader than these topics, touching on disciplines as diverse as economics, climate modeling, agriculture, psychology, and philosophy. The metadata reveal that there are around 150 documents published on GCR/ER each year, the field has highly unequal gender representation, most research is done in the United States and the UK, and many of the published articles come from a small subset of authors. We recommend creating new conferences and potentially new journals where GCR/ER-focused research can aggregate, making gender and geographic diversity a higher priority, and fostering synergies across clusters to think about GCR/ER in a more holistic way. We also recommend building more connections to new fields and neighboring disciplines, such as systemic risk and policy, to encourage cross-fertilization and the broader adoption of GCR/ER research.