Stormy Dwarfs, Gentle Giants: A Radio View of Stars and How They Shape Their Environments Radio observations trace phenomena in the outer atmospheres of stars and brown dwarfs, including winds, chromospheres, and coronae. Radio wavelengths also offer unique diagnostic power for non-thermal processes such as flares, shocks, and auroral current systems. Radio observations of these magneticallymediated particle acceleration processes enable diagnosis of magnetic field strength, particularly significant for brown dwarfs and extrasolar planets. Radio also offers the potential to detect stellar eruptions and energetic particle events that shape the environment experienced by planets. Efforts to observe these processes at radio wavelengths, currently in their infancy, will become increasingly significant with the advent of ever-more-sensitive radio facilities, especially low-frequency facilities with wide area coverage. These developments coincide with a growing recognition of space weather as a key element of exoplanet characterization. Efforts to study extrasolar space weather are informed by solar physics, where radio observations play a significant role in studying magnetic fields and plasma properties, particle acceleration, and space weather events. Radio studies of low-mass stars have traditionally focused on non-thermal processes, since the small stellar size implied that thermal sources were too faint to detect. Radio facilities are now attaining the sensitivity needed to detect the quiet radio Sun at stellar distances, enabling study of thermal emission from chromospheres and coronae of low-mass stars, which can be used to infer atmospheric temperature profile and trace magnetic activity cycles. In massive or giant stars, radio telescopes can detect, and even image, thermal emission from the photosphere, chromosphere, or wind, enabling measurement of wind mass loss rates and atmospheric structure. Across the HR diagram, stellar radio astronomy is benefiting from recent and upcoming improvements in sensitivity and bandwidth, which support time-resolved, multi-frequency studies of dynamic processes in stellar atmospheres.