House Pseudonym

A House Pseudonym is a pen name that can be used by any writer at a given publisher.

House Pseudonyms have been used to disguise that a long series has become a Franchise Zombie by allowing other authors to use the creator's name. They have been used to make a collaborative work look like it came from a single author, using a name that belongs to neither of the actual writers.

In the internet age, some websites use them as well. It may be a conscious decision, or it may be the byproduct of giving a standard moniker to posters who aren't signed into the site.

Literature

 * This article on The Other Wiki will tell you some of them.
 * Carolyn Keene of the Nancy Drew novels.
 * Franklin W. Dixon of The Hardy Boys novels.
 * K. A. Applegate of Animorphs.
 * R. L. Stine of Goosebumps.
 * VC Andrews -- enough that that "author" has been publishing long after Author Existence Failure.
 * Victor Appleton of the Tom Swift books.
 * Victor Appleton II of the Tom Swift, Jr. books.
 * Maxwell Grant of the Shadow novels (usually Walter B. Gibson).
 * Kenneth Robeson of the Doc Savage novels (usually Lester Dent).
 * Inverted with Harry Potter. Due to the great complexity of the series, several readers thought Harry Potter was the work of multiple authors; however, J.K. Rowling rebuked those claims by stating seriously it's just me much to the awe of this disbelieving side of the fanbase.
 * Erin Hunter of Warrior Cats
 * James Axler of the Deathlands series and its spinoff, Outlanders

New Media

 * People who sign up for free webhosting services are a (virtual) example of this trope.
 * Amazingly, few webhosts seem to check if signups really are this - this webhosting management discussion site is one such example. But, due to a bizarre Finagles Law and legalities, amazingly, it's legal.
 * Which leads to sign-ups with placeholder numbers, like (Manchester phonecode here) 0161 000 0000.
 * "Anonymous Coward" at Slashdot.
 * "Anonymous" at 4chan.
 * The authors of this roads and traffic blog. Perhaps because he doesn't wish to compromise his identity.
 * Anonymous, the well-known "hacking" group. The one with the question mark and suit logo.