Best Selling Comics
A list with a caveat
The caveats: comic books used to sell literally millions of copies for single issues. In an interview with Neal Adams I read back in the1970s or 1980s, he said something along the lines of that a series selling only half a million copies at DC Comics was in danger of getting cancelled (this was in relation to his Green Arrow/Green Lantern series).
Another comparison: consider this statement that Uncle Scrooge and Walt Disney Comics and Stories were selling over one million copies each in 1960 (info at comichron).
Also, consider this article at Comics Beat: "[1940s Comic Book publisher] McKay, ...was publishing five or six titles with an annual sale in excess of twenty-five million copies...” And that's just one publisher out of a field of many dozens.
The list below based partially on the "top ten" list (with cover illos) at Polygon.
Best selling comic books of all time
2018 Action Comics #1000 - 504,200 copies
1992 Amazing Spider-Man sold 519,804 copies on average per issue and had 25,096 subscribers
2019 Detective Comics #1000 - 526,941 copies
2009 Amazing Spider-Man #584 (Pres. Obama Cover) - 530,500 copies
2015 Secret Wars #1 - 550,500 copies
2014 The Amazing Spider-Man #1 - 559,200 copies
2002 Ultimate Spider-Man #1 - 631,990 copies
2002 Batman: The Ten Cent Adventure - 702,126 copies
2002 Fantastic Four #60 - 752,699 copies
2015 Star Wars #1 - 1,073,000 copies
1992 Superman #75 "Death of Superman" - est. 6 million copies sold
1991 X-Men #1 - 8,186,500 copies
Original Page Aug 2019
The Spectre - Volume 1 (DC Archive Editions)