An extremely devoted follower of a particular media (i.e. film, film director, band, TV series, writer) who takes their love a step further by deriding those who have an opposing opinion. Early use of the term had been directed to anime and Stars Wars "geeks". However, growing popularity of both has limited this stereotype and "newer" fanboy subjects tend to be more polarizing in popularity. Typically, fanboys spend their time lurking around internet messageboards, calling any detractor of their media a "troll", "idiot" or just allege detractor(s) don't "understand" particular subject. Knee-jerk responses like this (over rational, intelligent discussion) makes for quick and easy attribution. Fanboys are also known for creating their own realities and interpretations of their beloved subjects.

The nu-metal band Tool and film director Wes Anderson are both noted for having fanboy followings.
TARANTINO FANBOY: I just watched "The Untouchables" last night, wow did that movie rip off "Pulp Fiction"!

NOT A FANBOY: Did Brian DePalma time travel 7 years ahead of 1987? I didn't know they had that technology back then.

TARANTINO FANBOY: OK, well then, "City on Fire" ripped off "Reservoir Dogs", the plot similarities are too close for comfort!

NOT A FANBOY: I guess Ringo Lam must have time traveled as well, because City of Fire was also released in 1987, well before Reservoir Dogs.

TARANTINO FANBOY: That is a lie! U R nothing but a Tarantino hater, U should stick to Disney and the Family Channel and leave the unique original filmmaking up to US!!!!!
by ChoWares December 8, 2007
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The rare form of the fangirl interested in celebrities and fictional characters as well as "geek cultures" (Doctor Who, Star Trek, etc.) If you find a fanboy you should contact the nearest fangirl immediately, as they are an endangered species.
"Hey check out my David Tennant trench coat, I got it for coaplaying this weekend!"
"Dude, I didn't know you were a fanboy!"
by Aim Hemmings July 2, 2015
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Someone who has devoted their entire consciousness and personality to a random form of capitalistic media. Commonly found amongst gamers, music listeners, celebrity worshipers, anime freaks, etc. Will not hesitate to bash the living shit out of anyone who doesn't like what they like with such callous and witty insults as "fag" "fAg" and "FAG."
Fanboys don't realize that Sega, Sony, Nintendo, etc. all make good and bad products alike.
by C-can October 21, 2003
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A fanboy is an obsessed fan of a specific anime, video game, or some other media, often hostile to those who disagree. Anime fanboys or otaku might engage is cosplaying, writing fanfiction, or creating fanart. Other fanboys (or the female equivelant, fangirls) of other media might do similar things and also act hostile towards those who disagree.
I just got flamed by some Naruto fanboy simply because I said it was an overrated anime.
by King of Jellybeans November 11, 2007
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Well, in the case of Urban Dictionary, it's someone who's only posted one definition, and that definition always bashes some other system.
I believe we all know what a fanboy is.
by spel itt rite March 14, 2006
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Plural for fanboy. People who are obsessed with one thing and try to model their lives around that one thing. Examples are furries, anime fanatics, and Megatokyo readers.
Wapanese are examples of fanboys.
by otaku killer October 9, 2003
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A fan of a certain thing who will tolerate no criticism of that thing. Most often associated with "nerdy" subjects, especially the video gaming community. Most people are likely to encounter fanboys over the Internet, as the veil of anonymity allows the fanboy to be as aggressive and arrogant as he likes without the possibility of reprisals.
Ordinary, well-adjusted game player: "Good game everyone."

Hulking, stinking, fast-food loving arrogant fanboy: "OMFG YOUR A NOOB LOL I COULD KICK UR ASS UR MOM (etc.)"
by Muttering Master March 6, 2007
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