Firstly, what is a meme? A meme is an image, video, picture or
piece of text that is typically humorous in nature that spreads
like wildfire on the Internet. It can also be defined as a virally
transmitted cultural symbol or social idea. Some examples of memes
would be the well-known "dancing baby" or the following
images *for those that are Game of Thrones fans:

It's probably appropriate for me to enter the following
disclaimer at this point:
The above images are used purely for illustrative
purposes.
In Copyright terms, a meme would be considered a derivative work
in the sense that it is a copy of another work. Copyright
protection would be afforded to the owner of the work that has been
copied. As such, it is typically the owner of the original work
that has been copied that would be entitled to create and then
share derivative works.