Baki the Grappler (Japanese: グラップラー刃牙, Hepburn: Gurappurā Baki) is a Japanese manga series written and illustrated by Keisuke Itagaki. It was originally serialized in the shōnen manga magazine Weekly Shōnen Champion from 1991 to 1999 and collected into 42 tankōbon volumes by Akita Shoten. The story follows teenager Baki Hanma as he trains and tests his fighting skills against a variety of different opponents in deadly, no-rules hand-to-hand combat.

The series was followed by five sequels in the same magazine; Baki (バキ, officially romanized as New Grappler Baki: In Search of Our Strongest Hero), which was serialized from 1999 to 2005 and collected into 31 volumes, Baki Hanma (範馬刃牙, Hanma Baki, officially romanized as Baki: Son of Ogre), which was serialized from 2005 to 2012 and collected into 37 volumes, Baki-Dou (刃牙道, Baki Dō, lit. "Baki's Style"), which was serialized from 2014 to 2018 and collected into 22 volumes, a fifth series, also named Bakidou (バキ道) but with Baki's name written in katakana instead of kanji, serialized from 2018 to 2023 and collected into 17 volumes, and Baki Rahen (刃牙らへん, Baki Rahen, lit. "Baki and Others"), serialized from 2023.

A 45-minute original video animation (OVA) was released in 1994. A 24-episode anime aired on TV Tokyo between January 8 and June 25, 2001, and was quickly followed by a second 24-episode series from July 22 to December 24, 2001. An original net animation (ONA) was released on Netflix between June 25 and September 24, 2018, followed by a second season that was released on June 4, 2020. A third series was released from September 30, 2021 to August 24, 2023, and anime adaptation of Baki-Dou has been announced. The OVA was the first to be licensed and released in North America, in 1998 by Central Park Media, followed by the original manga series in 2002 by Gutsoon! Entertainment (incomplete), and finally both anime series in 2005 by Funimation Entertainment. Media Do International began releasing the second manga series digitally in August 2018.

The Baki series is one of the best-selling manga series of all time, with over 100 million copies in circulation.