This old edit on [[Holler]] is one of my favorites:
http://en.wikipedia.org/w/index.php?title=Holler&diff=5401691&oldid=...
The article went from bogus information on a purported Norse god to what looks like a probable copyvio on a Spice Girls single. (If there was an online source it can't be found anymore.)
On the Norse mythology articles, which is my primary sphere of interest on Wikipedia, irrelevant fancruft tends to accumulate and distract from the main content of the entries.
For an example see [[Yggdrasil]] which has a large Popular Culture section and a disambiguation entry, both of which could be summarized with "a bunch of things in a bunch of games/novels/etc. have been named after the mythological Yggdrasil".
Sometimes I snap and delete some of the stuff. For example I removed the following from [[Fenrisulfr]]:
"Fenrir appears as a summonable character in Squaresoft's Final Fantasy IX. Also it is a summonable creature in Final Fantasy XI."
Recently, of course, the poor wolf got this added to the top of his page:
"For the character from the Harry Potter novel, see Fenrir Greyback."
The article on [[Nótt]] the personification of "night" in Norse mythology had this at its top:
"For the Harry Potter character, see Minor Dark wizards in Harry Potter."
The irony here is that a bunch of real people have been named "Nott" and singling out a *minor* dark wizard from the Harry Potter books is patently absurd.
I don't actually mind fancruft. I can even appreciate that there are probably more people who care about Harry Potter mythology than Norse mythology. But still, I don't want it in my face all the time :)
Regards, Haukur