Realists are the theorists of power politics. Although realists base their analysis of international politics on the role of power, there is a good deal of variation in how individual realist scholars conceptualise the concept. The article makes use of the important insight that rather than being monolithic, there actually are a number of different and competing realist theories. It closely examines how classical, structural, and modified realists understand and employ 'power' with the underlying aim to determine how each version of realism comprehends this elusive concept.