Nexus: A Sci-Fi Inspiration and Collaboration Platform is a UX/UI design project that reimagines how science fiction communities engage online. Drawing from user research, platform case studies, and speculative design, Nexus addresses the fragmented experience found on platforms like Reddit, X, and Instagram. It introduces features like The Lab, a concept-driven filtering system, and Nex, an AI assistant tailored to sci-fi discovery and creativity. These tools help users explore speculative ideas more intentionally, with an interface rooted in retro-futuristic aesthetics and compact, functional layouts. This project was developed through iterative prototyping, informal user feedback, and analysis of digital community behavior. It bridges inspiration and utility by offering a structured, genre-aware environment for creators, fans, and thinkers alike. Nexus demonstrates how thoughtful UX design can transform niche interest groups into collaborative, idea-driven ecosystems.