As XR and AI extend our abilities, they transform our self-conceptions and relationships, blurring individual and collective identity. Drawing from psychology research, tech startups, artists, and IDEO's emerging tech group, we'll explore the fluidity of selfhood and mind-expanding possibilities of immersive shared spaces. These imagination playgrounds offer glimpses into others' perspectives, dissolve barriers, and empower new collaboration. As we become more able to define and redefine ourselves with these tools, we'll need to grapple with the question of what a "self" really is.