From Fan History Wiki
FanPop is a multifandom link site and community for fans of all things related to fandom. The site is based out of California and is run by a number of guys. The site advertised heavily on TV Guide's website and TV Guide helped to promote them which helped their early growth. The site mostly contains links to videos, polls and links.
In September 2008, it was discovered that a number of photmanips, images and icons were posted on FanPop in the CSI spot with out proper crediting of images.  // August 2009, it was discovered that all of the manipulation, images, blends, icons, are posted without credit, editting, and without following the rules of the artist. Especially on the Harry Potter Clubs, and Shipping Clubs.
There are a number of fandoms represented on FanPop and there size keeps growing. The size of the FanPop community has very little relationship with the size of the fandom on places like FanLib, FanFiction.Net, Yahoo!Groups and LiveJournal.
- FanPop: Official site