Cover date in the context of "Detective Comics"

Iron Man is a superhero appearing in American comic books published by Marvel Comics. Co-created by writer and editor Stan Lee, developed by scripter Larry Lieber, and designed by artists Don Heck and Jack Kirby, the character first appeared in Tales of Suspense #39 in 1962 (cover dated March 1963) and received his own title with Iron Man #1 in 1968. Shortly after his creation, Iron Man became a founding member of the superhero team, the Avengers, alongside Thor, Ant-Man, the Wasp, and the Hulk. Iron Man stories, individually and with the Avengers, have been published consistently since the character's creation.

Iron Man is the superhero persona of Anthony Edward "Tony" Stark, a businessman and engineer who runs the weapons manufacturing company Stark Industries. When Stark was captured in a war zone and sustained a severe heart wound, he built his Iron Man armor and escaped his captors. Iron Man's suits of armor grant him superhuman strength, flight, energy projection, and other abilities. The character was created in response to the Vietnam War as Lee's attempt to create a likeable pro-war character. Since his creation, Iron Man has been used to explore political themes, with early Iron Man stories being set in the Cold War. The character's role as a weapons manufacturer proved controversial, and Marvel moved away from geopolitics by the 1970s. Instead, the stories began exploring themes such as civil unrest, technological advancement, corporate espionage, alcoholism, and governmental authority.

Action Comics #1 (cover dated June 1938) is the first issue of the original run of the comic book/magazine series Action Comics. It features the first appearance of several comic-book heroes—most notably the Jerry Siegel and Joe Shuster creation, Superman—and sold for 10 cents (equivalent to $2 in 2024). It is widely considered to be both the beginning of the superhero genre and the most valuable comic book in the world. Action Comics ran for 904 numbered issues (plus additional out-of-sequence special issues) before it restarted its numbering in the fall of 2011. It returned to its original numbering with issue #957, published on June 8, 2016 (cover-dated August) and reached its 1,000th issue in 2018.

On August 24, 2014, a copy graded 9.0 by CGC was sold on eBay for $3,207,852 USD (equivalent to $4,260,000 in 2024); it was the first comic book to have sold for more than $3 million for a single original copy.

Batman is an ongoing superhero comic book series published by DC Comics, featuring the character of the same name as its protagonist. The character, created by Bill Finger and Bob Kane, first appeared in Detective Comics #27 (cover dated May 1939). Batman proved to be so popular that a self-titled ongoing comic book series began publication with a cover date of spring 1940. It was first advertised in early April 1940, one month after the first appearance of his new sidekick, Robin the Boy Wonder. Batman comics have proven to be popular since the 1940s.

Though the Batman comic book was launched as a quarterly publication, it later became a bimonthly series through the late 1950s, after which it became a monthly publication.

Action Comics #1000 (cover dated Early June 2018) is the 1,007th issue of the original run of the comic book/magazine series Action Comics (after special #0 and #1,000,000 tie-ins to Zero Hour: Crisis in Time! and DC One Million respectively; a second #0 in 2012; and #23.1, #23.2, #23.3, #23.4 in 2013). It features several Superman stories from a variety of creators, including previously unpublished artwork by Curt Swan, who drew Superman for nearly four decades. It was a commercial and critical success, being the most-ordered comic of the month.

Superman is an ongoing American comic book series featuring the DC Comics superhero Superman as its protagonist. Superman began as one of several anthology features in the National Periodical Publications comic book Action Comics #1 in June 1938. The series proved so popular that National launched Superman into his own self-titled comic book, the first for any superhero, premiering with the cover date summer 1939. Between 1986 and 2006 it was retitled The Adventures of Superman, while a new series used the title Superman. In May 2006, it was returned to its original title and numbering. The title was canceled with issue #714 in 2011, and was relaunched with issue #1 the following month which ended its run in 2016. A fourth series was released in June 2016 and ended in April 2018, while the fifth series was launched in July 2018 and ended in June 2021. The series was replaced by Superman: Son of Kal-El in July 2021, featuring adventures of Superman's son, Jon Kent. A sixth Superman series was released in February 2023.

The Flash is the name of several superheroes appearing in American comic books published by DC Comics. Created by writer Gardner Fox and artist Harry Lampert, the original Flash first appeared in Flash Comics #1 (cover-dated January 1940, released November 1939). Nicknamed "the Scarlet Speedster", all incarnations of the Flash possess "superspeed", which includes the ability to run, move, and think extremely fast, use superhuman reflexes, and seemingly violate certain laws of physics.

Thus far, at least five different characters –each of whom somehow gained the power of "the Speed Force"– have assumed the mantle of the Flash in DC's history: college athlete Jay Garrick (1940–1951, 1961–2011, 2017–present), forensic scientist Barry Allen (1956–1985, 2008–present), Barry's nephew Wally West (1986–2011, 2016–present), Barry's grandson Bart Allen (2006–2007), and Chinese-American Avery Ho (2017–present). Each incarnation of the Flash has been a key member of at least one of DC's premier teams: the Justice Society of America, the Justice League, and the Teen Titans.

Doctor Sivana is the name of two fictional, related characters appearing in American comic books published by DC Comics. The original Doctor Sivana's alter-ego is Thaddeus Bodog Sivana, a recurring enemy of the superhero Captain Marvel created by Bill Parker and C. C. Beck and first appeared in Whiz Comics #2 (cover-dated February 1940) by Fawcett Comics. A mad scientist and inventor bent on world domination, the character was established as Captain Marvel's main archenemy during the Golden Age, appearing in over half of the Fawcett Captain Marvel stories published between 1939 and 1953. Thaddeus has kept his role as one of the key archenemies of Captain Marvel (now Shazam) throughout the character's appearances in DC Comics, which eventually acquired the rights to Fawcett's superhero characters. In 2009, Doctor Sivana was ranked as IGN's 82nd-greatest comic book villain of all time.

The second character known as Doctor Sivana is Georgia Sivana, P.h.D, the daughter of Thaddeus who first appeared in Mary Marvel #1, created by Otto Binder. Georgia was originally portrayed as an underling of her father who takes after her father in appearance and skills, both possessing keen scientific minds although the character is instead an arch-nemesis for Mary Marvel. Years following "The New 52" reboot and during the "Infinite Frontier" initiative, Georgia's character is revamped into an older professor, archaeologist, and estranged daughter of Thaddeus whose reputation is tarnished due to her father's obsession with magic in the scientific community and seeks to improve it at any cost.