When you get to a 404 error page you see this image,
I believe it is supposed to be a combination of the site logo and the site banner image. See the site logo:
Which the designer Jin describes as follows:
The logo for the site is the rune circle around the female warrior's silhouette. It's not actually in the logo type "Science Fiction + Fantasy." I feel this placement sets the mood better in the header image.
And the site banner image featuring the Angel of Death: