'What makes an ideal keynote speaker? Someone who gives a fantastic address that offers the audience an overview of their work linked to the conference theme, something up to the minute, something new, something engaging, something a little edgy, a bird’s eye view of the issues at hand, without unnecessary jargon, but demonstrating keen insights, humour, passion and compassion. Someone who leaves the audience inspired, and a little star struck. But more than that, they should be someone who is present, engages with other presentations, asks gentle supportive questions, speaks equally to high flyers and lowly PhD students, joins in the social events, and shares their wisdom with modesty … basically they should be Stephen Castles at every conference we have ever had the pleasure of seeing him at. The authors both first met Stephen at conferences such as these. Farida, a long-time admirer and friend, when he keynoted at The Australian Sociological Association (TASA) conference in Perth, Western Australia in 2006, and Cat, an early career researcher and fan from afar, when he keynoted at the WA Migration and Mobilities Update conference in Perth in 2017.' (Introduction)