At the global level, viral epidemiology depends on modes of transmission and social networks; at the cellular level viruses repurpose protein interaction networks and remodel cellular compartments; on the local level the assembly and disassembly of a virus is governed by (and reveals) physical principles. Viruses also bridge multiple scientific disciplines. In biomedicine, understanding viral lifecycles provides essential information for developing antiviral agents that block infection. In more fundamental sciences, viruses are ideal model systems for studying mechanisms underlying self-assembly, genome packaging and release, allostery, membrane dynamics, and the efficient passage of nanoscale particles through membranes. The COVID-19 pandemic highlights the need for these cross-disciplinary approaches to understand viral biology, predict their global spread in impact, and develop new treatments. In addition to advancing antiviral strategies and cell biology, the knowledge acquired from these studies and the viral particles themselves are enabling researchers to engineer virus-based platforms for biomedical and nanomaterials applications, such as gene delivery or optoelectronics. This natural diversity requires collaborative efforts of researchers with a wide range of expertise.