Board Thread:Support Requests - Getting Started/@comment-25414732-20170629112211/@comment-168424-20170630221218

It depends on the wiki and the use. Generally if the image matches the topic of the wiki and the wiki is to promote information on the topic it falls under "fair use", but if it's for things like avatars or off topic uses, it can't really be defended legally.

Some images are supplied to the media with what are called embargo conditions where you aren't supposed to show anyone until a certain date. Uploading images before that date would also violate fair use.