Agile teams are often recognised for their speed and adaptability, but their true strength lies in something deeper: a shared team ethos. This chapter explores how team ethos, defined as the collective values, relational habits, and cultural norms that shape how teams work together to act as the invisible engine of Agile success. Drawing on insights from practice and theory, it reveals how shared values, distributed ownership, and mutual trust turn frameworks like Scrum into lived, resilient collaboration. From rituals and onboarding to conflict navigation and cultural diversity, the chapter shows that high-performing teams are not just aligned in tasks but connected in purpose. It argues that team ethos is a structural necessity, enabling cohesion, adaptability, and psychological safety. As Agile becomes increasingly global and virtual, the intentional cultivation and repair of ethos become essential. This is not about harmony or perfection but about fostering the conditions where people can collaborate authentically, take collective ownership, and grow together. Agile teams may deliver in code, but they thrive in culture, and it is their ethos that makes them endure.