Who's Who "The Definitive Directory of the DC Universe" is a twenty six issue series that served as an encyclopedia for nearly every character, location, team and alien race in the DC Universe. This first volume was published in 1985 and was inspired by Marvel's Official Handbook of the Marvel Universe volumes. The title was written and researched by a variety of comic book historians including; Len Wein, Marv Wolfman, Robert Greenberger, Peter Sanderson and E. Nelson Bridwell. Each character's prose entry was a comprehensive chronicle, garnished with a drawing by one of DC's many talents. Featuring artists such as Joe Orlando, Carmine Infantino, Jerry Ordway, Mike Zeck, Keith Giffen, Marshall Rogers, Murphy Anderson and Gil Kane, the project began with a wrap around cover by George Perez.
In certain cases the consensus among the various writers was in contradiction with general comic concepts. In one instance, a character was listed as having the first appearance in the wrong issue, simply because their first appearance had been in the last panel of the issue previous to the one listed. The writers justified this decision by stating that the character had appeared and hadn't done anything, and therefore had not really been introduced.
The first volume followed an alphabetic sequence and didn't differentiate between characters, teams, locations or other categories. The alphabetical format was followed throughout except for the final issue (#26) which continued the alphabetical format for the first part of the issue (which were from character Wizard to Zyklon) and then filled in the rest of the issue with obscure characters that had been "missed" on the first edit (such as Captain X or Angel and the Ape) or characters that had risen to prominence in the previous months since the launch of the series (such as Guy Gardner or the 1000.) The alphabetical sequence for the series was also responsible for the sometimes strange selection of character highlighted on the covers. Some of these were obvious (Batman or Superman) whereas others were not so much so (Killer Frost or Solomon Grundy), which occurred simply because the characters appearing in certain issues was dependent on the alphabetic order, and not for any theme. Thus many of the issues had a collection of characters prominently featured who were of secondary importance to the mainstream continuity of DC Comics.
The layout for the series was generally that each character would have a full page dedicated to them, though on occasion half pages were used for minor characters, and more prominent characters (such as Superman) received two pages.
The series was also noteworthy for its letter column, or somewhat of a lack thereof. In the letter column for the series (which was written on the inside of the back cover - a space usually reserved for advertisements), the editors simply made notes concerning the characters that had been missed, and justified their omission, or made note that they would be included later when it was possible (and did not reference who had sent the letters). The editors also mentioned as much as possible an update on when the characters in that particular issue had most recently been seen. Notably many characters of some prominence were omitted from the original volume, while "update" characters were included in later editions (even though these characters were often background characters with little lasting impact - for instance the Justice League International Embassy staff.) The series is equally notable for its complete lack of advertisements.
The series was followed by various other updates:
Who's Who: The Definitive Guide to the DC Universe Update '87
Who's Who: The Definitive Guide to the DC Universe Update '88
These followup volumes became partially necessary because of the impact of the massive crossover of Crisis on Infinite Earths. The Who's Who series was planned in part to make sense of the massive multiverse which DC Comics had incorporated into its canon through the purchase of outside companies (including Fawcett Comics and Charlton Comics) many of which were previously dealt with as having populated their own "Earth" inside of the DC multiverse. There were additionally continuity problems to sort out dealing with the continued inclusion of golden age characters (many of whom were grouped on Earth-2), but the crossover event effectively changed a lot of the canon of the company in the process.
In 1990, a different format was taken, by adding individual Who's Who entries into ongoing series' annuals:
Action Comics Annual #2
Batman Annual #13
Blackhawk Annual #1
Detective Comics Annual #2
Dr. Fate Annual #1
Flash Annual #3
Green Arrow Annual #2
Justice League International Annual #3
New Titans Annual #5
Question Annual #2
Secret Origins Annual #3
Swamp Thing Annual #5
Wonder Woman Annual #2
Other spin-off concepts were also introduced including Who's Who in Star Trek (as DC Comics had the comic book rights to Star Trek at the time) and Who's Who in The Legion of Super-Heroes.
The series was eventually relaunched in a different format in the series Who's Who in the DC Universe.