Given their ubiquitous presence as witnesses to school-yard bullying, the role of the 'bystander' has been studied extensively. The prevalence and behaviour of bystanders to cyberbullying, however, is less understood. In an anonymous, school-based questionnaire, 716 secondary school students from South-East Queensland reported whether they had witnessed traditional and/or cyberbullying, and how they responded to each type. Overlap in bystander roles between online and offline environments was examined, as was their relationship to age and gender. Students who witnessed traditional bullying were more likely to have witnessed cyberbullying. Bystanders' behaviour was sometimes similar in both contexts of traditional and cyberbullying, mainly if they were outsiders but half of the 256 students who reported witnessing both traditional and cyberbullying, acted in different roles across the two environments. The implications of the findings are discussed in the context of previous research on cyberbullying and traditional-bystanders. Future research should further explore the role of bystanders online, including examining whether known predictors of traditional-bystander behaviour similarly predict cyber-bystander behaviour.