Garp

Monkey D. Garp is an esteemed and formidable Marine vice admiral who holds immense renown and power. He is the father of Monkey D. Dragon, the paternal grandfather of Monkey D. Luffy, and the adoptive grandfather of Portgas D. Ace. Garp played a pivotal role in Ace's birth and raised a young Luffy, whom he later entrusted to the Dadan Family. Garp is recognized as one of the key figures, along with Kong, Sengoku, Shiki, Silvers Rayleigh, Tsuru, and Whitebeard, from the time when Gol D. Roger, the "Pirate King," was alive. His notable deeds as a Marine soldier, particularly during the God Valley Incident, earned him immense notoriety and prestige, leading to his recognition as the "Hero of the Marines." Despite being offered the rank of Admiral several times, Garp declined the promotion each time.

Garp is widely acknowledged as a living legend and one of the strongest Marines ever. In his prime, he was renowned for repeatedly cornering Gol D. Roger, the Pirate King, in battle, and Roger himself attests to their near-fatal encounters. Garp's formidable power and immense popularity led to him being offered the rank of Admiral several times throughout his career, but he rejected it each time. Together with Roger, he fought and defeated the Rocks Pirates, one of the most powerful pirate crews in history, which included some of the most legendary pirates such as Edward Newgate, Charlotte Linlin, and Kaidou, as well as Roger's most formidable rival, Rocks D. Xebec. This remarkable achievement earned Garp the title of "Hero of the Marines." Further proof of his sheer strength and might is seen when Garp defeated Don Chinjao with a single punch, almost killing him. Don Chinjao's bounty was worth 542,000,000 beli in his prime, and he was said to be capable of splitting a continent with a headbutt. This feat earned Garp the epithet, "Garp the Fist." Chinjao himself admits that during that time, all pirates viewed Garp as a fearsome "Devil."

Despite being 76 years old, Garp displayed remarkable strength by easily defeating Marco the Phoenix, Whitebeard's second-in-command, which even Kizaru and Akainu struggled to do. During the War of Marineford, Garp was so enraged that he would have killed Akainu if Sengoku hadn't stopped him. When it was revealed that Luffy is Garp's grandson, it elevated Luffy's fame as even Demaro Black used it to impersonate him. Charlotte Linlin also acknowledged Garp's legacy when Luffy challenged her. Garp's rebellion and reputation are so great that even the World Nobles fear him. He possesses exceptional Haki skills, particularly in Busoshoku Haki, which he uses to injure Luffy, bypassing his rubber body. Garp also demonstrated his mastery of Kenbunshoku Haki, with enough expertise to mentor others, such as Koby.

Garp's Busoshoku Haki skills enabled him to counter and crush Chinjao's Busoushoku Haki-enhanced head drill over 30 years ago, showcasing his superior mastery compared to Chinjao, a formidable Busoshoku Haki user in his own right. At Marineford, Garp managed to injure Marco despite him being in his regenerative phoenix form. He is also capable of using Kenbunshoku Haki, with Dr. Fishbonen recommending Koby to seek Garp's expertise on the matter. Despite Doll's attempts to dissuade him, Garp sailed to G-14 and yelled for Helmeppo to join him in rescuing Koby from the Blackbeard Pirates.