Characters, Cartoons & Art
This seems to be the area that causes so many problems, yet is relatively easy to understand!
Quite simply, if the character is under 18 - you can't post it in this forum - but you could in the Entertainment forum provided the discussion isn't of a sexual nature.
If we look at something like Twilight and Harry Potter, the vast majority of the characters are under 18, but the actors are over 18. Talking about how hot Edward is in Twilight will get a post removed, but talk about Robert Pattinson being hot, and you're okay.
Special care should be taken with Manga and Yaoi because so many of the characters are minors - as are some of Marvel Comic's characters. A wikipedia search normally clarifies their age.
This may seem rather stupid, however it is an off-shoot from a legal ruling made in 2008 regarding 'Virtual Child Porn', and we have to be mindful of it's implications.