Cassandra Cain (also known as Cassandra Wayne) is a fictional superhero appearing in American comic books published by DC Comics, commonly in association with the superhero Batman.
 Created by Kelley Puckett and Damion Scott, Cassandra Cain first appeared in "Batman" #567 (July 1999).
 The character is one of several who have assumed the role of Batgirl, and Cassandra Cain goes by the name of Orphan in current DC Comics continuity.
Captain Marvel, also known as Shazam ( ), is a fictional superhero appearing in American comic books published by DC Comics.
 Artist C. C. Beck and writer Bill Parker created the character in 1939.
 Captain Marvel first appeared in "Whiz Comics" #2 (cover-dated Feb. 1940), published by Fawcett Comics.
 He is the alter ego of Billy Batson, a boy who, by speaking the magic word "SHAZAM" (acronym of six "immortal elders": Solomon, Hercules, Atlas, Zeus, Achilles, and Mercury), can transform himself into a costumed adult with the powers of superhuman strength, speed, flight, and other abilities.
Roy Harper is a fictional superhero appearing in American comic books published by DC Comics.
 Roy is one of DC's most longstanding characters, originating in 1940s comics as Speedy, the teen sidekick of the superhero Green Arrow.
 Like his mentor Green Arrow, Roy is a world-class archer and athlete who uses his exceptional marksmanship to fight crime.
 Along with other prominent DC Comics superhero sidekicks, he goes on to become a core member of the superhero group the Teen Titans.
 As an adult, Roy casts off his Speedy identity to establish himself as the superhero Arsenal, and for a time adopts the name Red Arrow to symbolise his having become an equal of Green Arrow.
 As well as continuing to serve as one of the Titans at various times, Roy has had leading roles in the superhero groups the Seven Soldiers of Victory, the Outsiders, the Justice League, and the Outlaws.
Cyborg (Victor "Vic" Stone) is a fictional superhero appearing in American comic books published by DC Comics.
 The character was created by writer Marv Wolfman and artist George Pérez and first appears in a special insert in "DC Comics Presents" #26 (October 1980).
 Originally known as a member of the Teen Titans, Cyborg was established as a founding member of the Justice League in DC's 2011 reboot of its comic book titles and subsequently in the 2016 relaunch of its continuity.
John Stewart, one of the characters known as Green Lantern, is a fictional superhero appearing in American comic books published by DC Comics and was the first African-American superhero to appear in DC Comics.
 The character was created by Dennis O'Neil and Neal Adams, and first appeared in "Green Lantern" #87 (December 1971).
Doctor Richard Occult is a fictional superhero appearing in American comic books published by DC Comics.
 Created by Superman's creators Jerry Siegel and Joe Shuster, Doctor Occult, also known as the Ghost Detective, is a private investigator and user of magic who specializes in cases involving the supernatural.
 Doctor Occult is the earliest character created by DC Comics still currently used in the DC Universe.
Oggar, the World's Mightiest Immortal is a fictional character from the publisher Fawcett Comics, whose publication rights were acquired by DC Comics in the 1970s.
 Oggar was a villain of Captain Marvel chronology in Pre-Crisis; he made no Post-Crisis appearances.
 He first appeared in "Captain Marvel Adventures" # 61 (May 1946, Fawcett Comics).
 His first appearance in DC Comics was in "World's Finest Comics" # 264 (August 1980).
Barbara Gordon is a fictional superhero appearing in American comic books published by DC Comics, commonly in association with the superhero Batman.
 The character was created by William Dozier, Julius Schwartz, and Carmine Infantino.
 At the request of the producers of the 1960s "Batman" television series, DC editor Schwartz called for a new female counterpart to the superhero Batman that could be introduced into publication and the third season of the show simultaneously.
 The character subsequently made her first comic book appearance as Batgirl in "Detective Comics" #359, titled "The Million Dollar Debut of Batgirl!"
 (January 1967), by writer Gardner Fox and artist Carmine Infantino.
Superman is a fictional superhero appearing in American comic books published by DC Comics.
 The character was created by writer Jerry Siegel and artist Joe Shuster, high school students living in Cleveland, Ohio, in 1933.
 They sold Superman to Detective Comics, the future DC Comics, in 1938.
 Superman debuted in "Action Comics" #1 (cover-dated June 1938) and subsequently appeared in various radio serials, newspaper strips, television programs, films, and video games.
 With this success, Superman helped to create the superhero archetype and establish its primacy within the American comic book.
 The character is also referred to by such epithets as the Big Blue Boy Scout, the Man of Steel, the Man of Tomorrow, and the Last Son of Krypton.
Supergirl (also known as Cir-El or Cheryl Kent) is a fictional superhero appearing in American comic books published by DC Comics.
 The character is best known as one of the characters to have assumed the mantle of Supergirl.
 Created by writer Steven Seagle and artist Scott McDaniel, she first appeared in "Superman the 10 Cent Adventure" #1 (2003) as the alleged daughter of Superman.
 She is later found to be a human girl who was genetically altered by the villain Brainiac to appear Kryptonian.
 The character dies thwarting a plot involving Brainiac 13. "
Superman" (vol.
 2) #200 implies that when the timeline realigned itself, Cir-El was erased from existence.

Question: Who is the publisher of the World's Mightiest Immortal , a fictional character, who is a villain to a fictional superhero appearing in American comic books published by DC Comics also known as Shazam ?
Answer: Fawcett Comics