As is often pointed out, in Bram Stoker’s orginal novel Dracula, the title character had no vulnerability to sunlight, but since then the concept of vampires being unable to tolerate sunlight has become iconic. Tolkien’s Orcs have also become an archtype common to fantasy and roleplaying. The Tropes page http://tvtropes.org/ lists hundreds of things that have been featured so often in works of fiction that they have become canonical across multiple different sources.
So for those who write (or just daydream a lot about) fantasy, science fiction, or other genres, is there one thing that you’ve thought of that you wish would become a meme? Some idea that you think fits perfectly, and would be proud to say you were the originator of?
(This is a slightly different question from asking “what do you wish you could declare was canon within a fictional universe”, but I’ll entertain suggestions about those too)