Wildlife, as well as human beings, are prone to be affected by fear. Large predators and mesopredators usually produce this fear in animals. This effect is recognised in the form of various behavioural changes and adaptations, which, in turn, affects the whole ecosystem. However, we often overlook the role of large predators and mesopredators in the sustenance of our ecosystem by such non-lethal effects, because fear is often seen as a psychological effect rather than something that can be found through explicit scientific means. Indeed, the fear that predators trigger inside their prey may play a significant role in the maintenance of the natural environment. This paper aims to analyse this hypothesis by reviewing the function of the ecology of fear based on the interaction among predators, prey, and mesopredators. We consider the factors involved in the effective functionality of the ecology of fear, including habitat landscape, season, weather, and predation risk. We also assess the extent of influence of large predators on behaviour and distribution of prey and mesopredators in terms of predation cues and prey grouping as responses to predation risk. Finally, we discuss the implications of fear ecology for wildlife conservation and management and new challenges.