MOOCs - massive open online courses - have emerged as the dominant topic in online education in New Zealand and elsewhere. MOOCs have been variously described as a tsunami, a paradigm shift and a disruptive force to both place-based and online tertiary education. This paper offers a comprehensive description of MOOCs and discusses key disruptive aspects of MOOC-based education such as university/student disengagement, low completion rates, peer assessment and business models.