The name Abdul Alhazred is a pseudonym that Lovecraft created in his youth, which he took on after reading 1001 Arabian Nights at the age of about five years. The name was invented either by Lovecraft, or by Albert Baker, the Phillips' family lawyer. Abdul is a common Arabic name component (but never a name by itself; additionally the ending -ul and the beginning Al- are redundant), but Alhazred may allude to Hazard, a pun on the book's destructive and dangerous nature. It might also have been a pun on "all-has-read", since Lovecraft was an avid reader in youth, or a reference to Lovecraft's ancestors by that name

Another possibility, raised in an essay by the Swedish fantasy writer and editor, Rickard Berghorn, is that the name Alhazred was influenced by references to two historical authors whose names were Latinized as Alhazen: Alhazen ben Josef, who translated Ptolemy into Arabic; and Abu 'Ali al-Hasan ibn al-Haytham, who wrote about optics, mathematics and physics. Ibn al-Haytham is said to have pretended to be mad to escape the wrath of a ruler.

Abdul Alhazred is not a real Arabic name, and seems to contain the Arabic definite article morpheme al- twice in a row (anomalous in terms of Arabic grammar). The more proper Arabic form might be Abd-al-Hazred or Abdul Hazred. In Arabic translations, his name has appeared as Abdullah Alḥaẓred (عبدالله الحظرد): Arabic ḥaẓraحظر = "he fenced in", "he prohibited". Hazred could come from the Persian or Arabic word "Hazrat" meaning Great Lord with a twist that makes it sound like "red" and "hazard" both indicative of danger. However Abdul is a common Arabic prefix meaning "Servant of the" and "Al" is Arabic for "the", and if "hazra" means "he prohibited", "he fenced in" or "Great Lord", then the name would mean "Servant of the Prohibited", "Servant of the Fenced in", or "Servant of the Great Lord" which would make sense considering his role, even if it is not a proper Arabic name.

Similarly, an article (written from an in-universe perspective) in the Call of Cthulhu roleplaying game speculates that it may be a corruption of Abd Al-Azrad, which it claims translates to The Worshipper of the Great Devourer.

The phrase "mad Arab", sometimes with both words capitalized in Lovecraft's stories, is used so commonly before Alhazred's name that it almost constitutes a title. A reference to the "Mad Arab" in Cthulhu Mythos fiction is invariably a synonym for Abdul Alhazred. However due to political correctness later writers sometimes preface Alhazred with words such as "monk" (such as in the Chick parody tract "Who will be Eaten First?" by Howard Hallis) or "scholar" replacing Arab to avoid any possible racist overtones.

According to Lovecraft's "History of the Necronomicon" (written 1927, first published 1938), Alhazred was:

In 730, while still living in Damascus, Alhazred supposedly wrote a book of ultimate evil in Arabic, al-Azif, which would later become known as the Necronomicon. Those who have dealings with this book usually come to an unpleasant end, and Alhazred was no exception. Again according to Lovecraft's "History":

August Derleth later made alterations to the biography of Alhazred, such as redating his death to 731. Derleth also changed Alhazred's final fate, as described in his short story "The Keeper of the Key", first published in May 1951. In the story, Professor Laban Shrewsbury (a recurring Derleth character) and his assistant at the time, Nayland Colum, discover Alhazred's burial site.

While the two are heading a caravan from Salalah, Oman, they cross the border into Yemen and find the unexplored desert area that the Necronomicon calls "Roba el Ehaliyeh" or "Roba el Khaliyeh" — presumably a reference to the Empty Quarter or "Rub al Khali".

At the center of the area they discover the Nameless City (the setting of the Lovecraft story of the same name) and in Derleth's text the domain of the Great Old One Hastur. Shrewsbury, an old agent of Hastur and the devoted enemy of Hastur's half-brother, Cthulhu, crosses its gates in search of Alhazred's burial site.