Introducing X1: The world's first multirobot system that integrates a humanoid robot with a transforming drone that can launch off the humanoid's back and, later, drive away. The new multimodal system is one product of a three-year collaboration between Caltech's Center for Autonomous Systems and Technologies (CAST) and the Technology Innovation Institute (TII) in Abu Dhabi, United Arab Emirates. The robotic system demonstrates the kind of innovative and forward-thinking projects that are