Blackbeard pirates. After Egghead, they got caribou. This is ofc the resolution to a 10 ish year old plotline where he follows the SH around and finds out about the ancient weapons. He knows where Pluton and Posidon are. Also, Blackbeard is the person at fault for Ace's death. This is because he was the one who originally captured and turned in Ace, this is significant because they were on a crew together, to someone like Luffy betraying your comrades is the worst of crimes. Pre time skip literally ends with Blackbeard becoming the first person to ever eat 2 devil fruits, tricking the WB pirates and Marines to fight eachother while he gained in power and position. Since then in the time skip, he has attacked almost everyone Luffy cares about, including the revolutionaries, Boa, Law, Pudding(this one is more so for Sanji, I guess) Koby, Garp, and we may be leading up to Shanks. We know he is of a "special bloodline" and Imu himself cuts up his posters with Luffy. Oda did not by accident give him the most iconic first impression and the name of the worlds most famous pirate.