Fanboys, the male equivalent of fangirls, are teenaged to fortysomething men who view television as at least a partial substitute for most other forms of human interaction. Especially those forms of interaction involving actual girls.
Though an increasingly rare group of fanboys devote themselves to the minute details of their favorite fictional worlds, poring over Star Trek technical manuals or writing software to mimic the operation of a Stargate, the majority mainly pine in a hopeless and somewhat disturbing fashion for the affections of wholly imaginary women. Common objects of fanboy desire over the years have included Dana Scully, Buffy the Vampire Slayer and/or her best friend Willow Rosenberg, Veronica Mars, pretty much every female cast member of Firefly, and The Golden Girls' Estelle Getty.
Many of these fictitious females are characterized by their apparent eagerness to sleep with nerds, geeks, dorks, and losers. Some were also created by lonely fanboys who simply lacked the drawing talent necessary to go into comics and draw big-breasted fantasy women who were hot for electrical engineers.
In television circles, Joss Whedon is a noted fanboy, as evidenced by his inability to write any form of filmed entertainment not involving adorable, ass-kicking young women with superpowers, up to and including his highly unorthodox BBC adaptation of Jane Austen's Emma.
Say what you will about fanboys, but at least they aren't heavily involved in the writing of slash fiction. Thank God.