G-REX is a novel dataset for real-world affective computing, with data collected in a naturalistic setting during movie sessions. Group physiological data (Photoplethysmography – PPG and Electrodermal Activity – EDA) are collected using a wrist-worn unobtrusive device and emotion ground-truth annotation is performed retrospectively, based on selected segments where each subject showed an elevated physiological response. In total, we provide data over 14 movie sessions, making a total of more than 300 hours of physiological data collected over 100+ subjects in groups.