That’s an interesting topic. According to Wikipedia, the best-selling comic series to date are:
- One Piece by Eiichiro Oda, with 516.5 million copies sold.
- Dragon Ball by Akira Toriyama, with 420 million copies sold.
- Asterix by René Goscinny and Albert Uderzo, with 385 million copies sold.
- Peanuts by Charles M. Schulz, with 300 million copies sold.
- Golgo 13 by Takao Saito, with 300 million copies sold.
These are based on the sales of collected comic book volumes, which include Japanese manga, American graphic novels, and European comic albums.
If you are looking for the best-selling single-issue comic books in America, Polygon has a list of the top 10, based on confirmed data from 1997 onward. They are:
- X-Men #1 (1991) by Chris Claremont and Jim Lee, with 8.1 million copies sold.
- Star Wars #1 (2015) by Jason Aaron and John Cassaday, with 1.07 million copies sold.
- Batman: The 10-Cent Adventure (2002) by Greg Rucka and Rick Burchett, with 1.06 million copies sold.
- The Amazing Spider-Man #583 (2009) by Dan Slott and Barry Kitson, featuring Barack Obama, with 530,500 copies sold.
- Detective Comics #1000 (2019) by various creators, celebrating Batman’s 80th anniversary, with 526,941 copies sold.