In ancient Chinese, “霸”(Hegemon) has the same meaning and announciation of “伯”， which means "the eldest son in a family", or "senator". Both "五霸" and "五伯" can be translated into "Five Hegemons".
Interestingly, while hegemony is often associated with states, during this period it was instead associated with individual rulers, namely the ones who have brought their respective states to a dominant position. In this sense the reigns of each hegemon tends to correspond with the zenith of their state's power.
The concept of hegemony arose out of the weakness of the Eastern Zhou Dynasty; while its predecessor, the Western Zhou Dynasty, was also feudal in nature, the centre was strong enough to command the obedience of most of its vassals, as well as upkeep a central army. The death of King You of Zhou and the sack of the Zhou capital in 771 BC rendered the position of the central court untenable and eventually dependent on the protection of neighbouring states.
These are the two most commonly-used lists of hegemons.
The first three hegemons are highly renowned, and therefore rarely disputed.