Refers to a person who has achieved dominance through military or political power, often in a historical or epic context.
彼は戦国時代の覇者として知られている。
He is known as a supreme ruler of the Warring States period.
He finally became the champion of Asia.
Commonly used in sports and competitions to refer to the reigning champion or titleholder.
彼は3年連続で覇者となった。
He became the champion for three consecutive years.
そのチームはリーグの覇者となった。
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'.