The narrator of "Shooting an Elephant" (a semi-autobiographical Orwell, speaking via his own experiences) fulfills the role of "ruler". The Burmese citizens are the "ruled". However, we might benefit by breaking down these terms even further.
There is both an abstract idea, and an embodiment, of the terms "ruler" and "ruled". In a sense, the abstract body of the British government is the actual ruler; the narrator is merely a person who happens to be acting on its behalf. He is no more a ruler than any other person, it is only by virtue of his birth as an English citizen that he happens to be on the ruling side. This, his reluctance for his position, and his love/hate relationship with the Burmese, complicate his identity as a ruler, and contribute to the modernist tone of the story.
Likewise, the role of "ruled" is complicated by the fact that the narrator is, largely, set against the entire town, and the people are the driving force behind the action. They caused the narrator to be worried for his pride, and his perception of them as distasteful "little beasts" make them seem less like rational humans, and more like temperamental animals; ruling them is more like herding them.
Thus, the roles of ruler and ruled are complex, and paradoxical; while the narrator is ostensibly the ruler and the Burmese the ruled, by virtue of their political relationship, the narrator in fact does not want to rule the Burmese (he even advocates on their behalf against the British), yet fulfills his duty more out of habit and a sense of pride instilled in him by his own society, not the Burmese. We might even see the narrator as the "ruled" himself, his rulers being both the Burmese population and the expectations of British society itself.