Eiichiro Oda (尾田 栄一郎 Oda Eiichirō, born January 1, 1975) is a Japanese manga artist, screenwriter and film producer who is best known for his manga series One Piece (1997–present). With 430 million copies in circulation worldwide, One Piece is the best-selling manga series of all time. The series' popularity resulted in his being named one of the manga artists that changed the history of manga. On June 15, 2015, it was announced that Eiichiro Oda and One Piece had set the Guinness World Record for "the most copies published for the same comic book series by a single author" with 320,866,000 copies printed worldwide as of December 2014.

Eiichiro Oda claimed that at age four he resolved to become a manga artist in order to avoid having to get a "real job". His biggest influence is Akira Toriyama and his series Dragon Ball. He recalls that his interest in pirates was probably sparked by the popular TV animation series titled Vicky the Viking. He submitted a character named Pandaman for Yudetamago's classic wrestling manga Kinnikuman. Pandaman was not only used in a chapter of the manga but would later return as a recurring cameo character in Oda's own works.

At the age of 17, Oda submitted his work Wanted! and won several awards, including second place in the coveted Tezuka Award. That got him into a job at the Weekly Shōnen Jump magazine, where he originally worked as assistant to Shinobu Kaitani's series Suizan Police Gang before moving to Masaya Tokuhiro on Jungle King Tar-chan and Mizu no Tomodachi Kappaman, which gave him an unexpected influence on his artistic style. At the age of 19, he began working as an assistant to Nobuhiro Watsuki on Rurouni Kenshin, before winning the Hop Step Award for new manga artists. Watsuki credits Oda for helping create the character Honjō Kamatari who appears in Rurouni Kenshin. During this time, Oda drew two pirate-themed one-shot stories called "Romance Dawn", which were published in Akamaru Jump and Weekly Shōnen Jump respectively in late 1996. "Romance Dawn" featured Monkey D. Luffy as the protagonist, who then became the protagonist of One Piece. In 1997, One Piece began serialization in Weekly Shōnen Jump and has become not only one of the most popular manga in Japan, but the best-selling manga series of all time. It sold 100 million collected tankōbon volumes by February 2005, over 200 million by February 2011,, had 320,866,000 copies printed worldwide by December 2014 and had 430 million volumes in circulation worldwide as of October 2017. Additionally, individual volumes of One Piece have broken publishing records in Japan. Volume 56 received the highest initial print run of any manga, 2.85 million copies, in 2009. Volume 57's print of 3 million in 2010 was the highest first print for any book in Japan, not just manga. A record that was broken several times by subsequent volumes and currently held by 67's 4.05 million initial printing in 2012. In 2013, the series won the 41st Japan Cartoonists Association Award Grand Prize, alongside Kimuchi Yokoyama's Nekodarake Nice. In a 2008 poll, conducted by marketing research firm Oricon, Oda was elected fifth most favorite manga artists of Japan. He shared the place with Yoshihiro Togashi, creator of YuYu Hakusho and Hunter × Hunter. In their 2010 poll on the Mangaka that Changed the History of Manga, Oda came in fourth. For the tenth One Piece animated theatrical film, Strong World, Oda created the film's story, drew over 120 drawings for guidance and insisted Mr. Children provide the theme song. Additionally, a special chapter of the manga was created and included in tankōbon volume 0, which was given free to attendees of the film and also contained his drawings for the film. Oda and Akira Toriyama created a 2007 crossover one-shot called Cross Epoch, that contains characters from Toriyama's Dragon Ball and Oda's One Piece. In 2013, they each designed a Gaist character for the video game Gaist Crusher.