* [[http://www.somethingpositive.net/sp12262006.shtml Fluffmodeus]] in ''WebComic/SomethingPositive'' was [[http://www.somethingpositive.net/sp01132007.shtml introduced out of spite]], but has actually been a well-received character.
* Maxim, the {{Bishonen}} Jägermonster of ''Webcomic/GirlGenius'', was originally created as a joke. But he was found so funny that he was added to the comic as-is.
** The same goes for the entire Jager race. In the first scene with Klaus, there was a big empty space next to him, so Phil drew a scruffy-looking soldier with sharp teeth.
* TheCyantianChronicles: [[http://akaelae.cyantian.net/2010/01/20/01202010/#comments This page of the comic ''Akaelae'']] The author posted this comment after speculation on who the involved characters were.
-->''[[WordOfGod Actually, these two are the last two cameos. It was never mentioned that they were involved as characters... it was just too fitting to pass up with the dialogue that came to mind.]]''
** Also, Cesilee's Diary was originally supposed to be only 6 strips long. It ended up far longer and was eventually combined with the former primary comic, Campus Safari.
* Vaarsuvius of ''Webcomic/TheOrderOfTheStick'' was originally intended to have a definite gender. [[ViewerGenderConfusion The fans did not]] immediately [[{{Elfeminate}} get this]], and Rich Burlew decided to leave it ambiguous for laughs. Nowadays, V's AmbiguousGender is both a RunningGag and in some places a dramatic plot point.
* A coloring error caused Webcomic/{{Precocious}}' Yvette to suddenly appear darker for a few days (compare her in [[http://www.precociouscomic.com/archive/comic/2011/09/23 this strip]] to her [[http://www.precociouscomic.com/archive/comic/2011/09/24 the next day]]). The author decided that she looked better this way and kept the new "dark Yvette"
* ''Webcomic/ElGoonishShive'': According to the commentary in [[http://www.egscomics.com/?date=2012-06-15 this]] strip the origin of the whole plot point of Nanase's rapid hair growth being magic related (and [[http://www.egscomics.com/index.php?arcid=99 the storyline]] it inspired) stemmed from [[http://www.egscomics.com/?date=2011-08-02 this]] strip in which Dan drew Nanase's hair too long too soon (given that it was only three weeks InUniverse since her last appearance when [[http://www.egscomics.com/?date=2011-01-03 her hair was much shorter]]).
-->''[[WordOfGod This put me in a position where I could either gloss over the oddly fast hair growth, or create some manner of convoluted explanation for it. Being me, I went the convoluted route.]]''
* A one-panel example in ''Webcomic/{{Concerned}}'': author Chris Livingston was in the middle of making a strip when his wife made the off-the-cuff request that, at some point of the comic's run, protagonist Gordon Frohman use the expression, "Eep". Livingston promptly put the expression directly into the panel he was working on at that exact moment -- thus having Gordon say "Eep" in response to [[MajorInjuryUnderreaction getting blasted in the chest with a shotgun]].
* DomainTnemrot: The referee was never meant to be named and would just be a background character. Fans loved him, so he was given a bigger role.
* Many elements of ''Webcomic/{{Digger}}'', including major characters and plot points, were invented on the spur of the moment.
* When the Commander and Jonesy went to the future in ''WebComic/ManlyGuysDoingManlyThings'', the chaos left behind in the present was originally just going to be generic chaos, but then ''LetsPlay/TwitchPlaysPokemonRed'' came out and Coelasquid was inspired to make a homage to it instead.
* ''Webcomic/KnightsOfBuenaVista'' does this InUniverse. Mary wants to give her PlayerCharacter policing skills, which is called "copper", but she wrote that for hair color, so others think this character is a RedheadedHero. Mary shrugs and goes with it.
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