One Piece has set the Guinness World Record for "most copies published for the same comic book series by a single author." Certainly a wordy title, though by no means less impressive. Series creator Eiichiro Oda commented on this accomplishment in a written statement:
"Thank you for this certification for the Guinness World Record. Manga is an amusing way to pass time, but when I receive reports that say 'through One Piece I made friends,' or 'through One Piece I found my sweetheart,' I am really happy. I feel like this record number has the possibility to bring the same number of people together. I will not forget my predecessors in the manga world, the colleagues whom I work with, and my readers, and from now on I want to continue to draw a work that will not shame this record."
As of the end of 2014, the manga has seen over 320,866,000 copies printed worldwide. It currently has 789 chapters, compiled into 77 volumes. Even with this incredible length, spanning 17 years of work, Oda doesn't seem to be interested in slowing down. Last year he said that he is constantly inspired for new material, and that he could go own drawing for another 10 years.
It looks like One Piece won't have to worry about someone else seizing the record just yet.