The life of Nick Kaiser was full of interesting adventures of all sorts beyond the contributions to astrophysics for which he is best known. He was an accomplished marathon and ultramarathon runner, an avid hiker, and always up for adventures of all sorts. Nick never finished high school on account of some chemistry experiments not fully appreciated by those in charge. Nevertheless, he made it to the University of Cambridge, where he received a PhD under Martin Rees. Kaiser went on to make numerous important contributions to cosmology. His work on gravitational lensing, peculiar velocities, and lensing by cosmic strings (the so-called Kaiser-Stebbins effect) are but a few examples.
He has received numerous honours for these contributions. Kaiser's professional trajectory spans the UK (IoA, Cambridge), United States (UC Berkeley and UC Santa Barbara), Canada (CITA, University of Toronto), Hawaii (where he was PI of pan-STARRS), and ENS, Paris, until his retirement in October 2022. Nick Kaiser was a frequent visitor at APC.
He was the PhD co-supervisor of Zheng Zhang at APC. He will be remembered for his inspiring talks filled with paradoxes that few could solve, his warmth, and engaging argumentative spirit that challenged those around him. He was a close friend to many at APC and will be greatly missed.