Gilthunder

Gilthunder is a former antagonist, turned into one of the main heroes of the manga, The Seven Deadly Sins, and its resulted anime series. A Holy Knight of the Kingdom of Liones, Gilthunder used to live and grow up with Meliodas, whom he teached him in becoming a respectful knight of the kingdom. At the beginning of the series, Gilthunder detested himself from Meliodas and the Seven Deadly Sins' faction, after being informed of their perjury by the Holy Knights Dreyfus and Hendrickson, hunting them down on several occasions. He eventually learned of the set-up and joined forces with Meliodas while begging for pardon for his actions against them. He also appears in the Worst Hero and Villain War Ever tournament as one of the main combatants on the villain alliance. Whether he would remain on the villain alliance or reform in the process of the series is currently unknown.