Refers to a person who has achieved dominance through military or political power, often in a historical or epic context.
He finally became the champion of Asia.
He is known as a supreme ruler of the Warring States period.
Commonly used in sports and competitions to refer to the reigning champion or titleholder.
He became the champion for three consecutive years.
That team became the league champion.
This year's champion will be decided in the final match.
勝者 simply means the winner of a single contest, whereas 覇者 implies a reigning, dominant champion over a whole competition or era.
優勝者 is the neutral, everyday word for the winner of a tournament, while 覇者 carries a grander, more dramatic tone of supremacy.
覇者 has a literary, historical flavor suggesting supremacy through conquest, while チャンピオン is the everyday word for a titleholder in sports or contests.
From Chinese 霸者 (bàzhě), meaning 'one who rules by force' or 'hegemon'. The kanji 覇 means 'supremacy' or 'domination', and 者 means 'person'.