Predator-prey interactions have strong effects on population dynamics and community structure, yet predators can also affect organisms through mechanisms other than predation. By altering the distribution of nutrients on the landscape, predators can affect soil nutrient dynamics and vegetation productivity, which could affect the distribution of herbivores and other wildlife. We examined the use of Arctic fox dens by mammalian herbivores and scavengers in western Hudson Bay in Canada and explored some of the mechanisms that may attract other wildlife and the benefits to their prey despite the apparent increased predation risk. Winter nests of lemmings, the primary year-round prey of Arctic foxes, occurred on over two-thirds of the fox dens visited each year. Vegetation on dens was more abundant, taller, and more nutritious (higher nitrogen content) than on off-den sites. The thicker snow in winter trapped by this vegetation on dens generated warmer subnivean temperatures that enhanced lemming reproduction, reflected in the size distribution of faeces in winter nests, suggesting fox dens may act as refuges for declining lemming populations by improving winter habitat. Motion-sensor trail cameras recorded more visits by caribou and scavengers to dens than control sites in summer, and the numerical response of mammalian scavengers to fox prey remains suggested they were attracted to these carcasses. These positive effects of ecosystem engineering contrast the negative effects of predation, highlighting the importance of integrating these dual roles for a broader understanding of the impact of predators on community dynamics.