For Halloween 2008, Wikipedians from various projects decided to give the Main Page a Halloween theme. The featured article of the day was Treehouse of Horror, special themed episodes of the long-running animated television series The Simpsons that are broadcast on or around Halloween. To date, 19 episodes have been created. The article itself became featured after its second candidacy at featured article candidates. Its main author is Scorpion0422, who is also the featured list director and author of a lot of other featured content, much being Simpsons related.
Did you know regulars decided to make a "themed" day of Halloween-related hooks. Normal rules of Did you know involve the article being created or expanded fewer than 5 days before nominating, but this rule was waived in order to prepare the nominations. In total, 28 new articles were created or expanded, ranging from the mythological Cerberus and the very real vampire moth, to candy pumpkins and phasmophobia, the fear of ghosts. There are currently plans to make a themed Did you know column for the Christmas period.
The Picture of the Day also featured a spooky theme, featured an image of two skulls demonstrating the location of Wormian bones can be. Wormian bones are, according to the article, "abnormal extra bone plates in the cranium".