Purpose: Non-technical errors (NTEs) contribute substantially to patient harm. Emergency general surgery is common, complex, and high-risk for NTEs, yet the incidence and characteristics of fatal NTEs remain unclear. This study aimed to characterise the incidence, clinical phase, team responsibility, and behavioural drivers of fatal NTEs in emergency general surgery to inform future non-technical skills (NTS) improvement strategies. Methods: A retrospective cohort study of all emergency general surgical mortalities with an adverse event or area of concern from the Australian and New Zealand Audit of Surgical Mortality (ANZASM) from 2012–2019 was conducted. Cases were independently assessed by two reviewers using a validated tool, with disagreements resolved by a third reviewer. Results: Fatal NTEs occurred in 790/1164 (67.9%) deaths, with a total of 1053 errors. Situational awareness errors were most common (518/1053, 49.3%), followed by decision-making (431/1053, 40.9%). Most errors arose from few recurrent behaviours: for situational awareness, failure to recognise clinical signs (92/518, 17.8%), failure to appreciate illness severity (75/518, 14.5%), missed diagnosis (73/518, 14.1%); for decision-making, failure to initiate appropriate intervention/investigation (99/431, 23%), incorrect operation (71/431, 16.5%). Error distribution differed across clinical phases (χ²=1325, p<0.01), with 947/1053 (89.9%) occurring outside the operating theatre. Surgical teams were responsible for 652/888 (73.4%) single-team and 109/116 (94%) multi-team errors; non-surgical teams for 235/888 (26.5%) single-team and 112/116 (96.6%) multi-team errors. Conclusions: Fatal NTEs mainly occurred outside the operating theatre, involved both surgical and non-surgical teams, and arose from few recurrent behaviours. These findings reveal a mismatch between traditional NTS improvement efforts and the contexts in which fatal NTEs occur, identifying actionable targets for future interventions.