You know a show has gone from "popular" to "something people unhealthily obsess over" when copious amounts of fan art starts to appear on the internet. The cool thing about fan art is that the end product of the obsession is normally applauded (when it's good) because it's directed towards a TV show, whereas you'd find yourself on the business end of a restraining order if it was directed, at say, that bank teller at your local branch who thinks you don't know how to work an ATM card.
So for our hump day Always Sunny Week installment (previously here and here) I've curated the Definitive Collection of Sunny Fan Art on the web. My definition for fan art -- much like definition for acceptable drinking -- is pretty broad so the collection ranges from graphics to drawings to paintings to photoshops to minimal posters to t-shirts to bobbleheads. The only thing I didn't include were prison sketches of the cast. They're pretty crude and remind me of that time I got shivved.
To keep this definitive, suggestions in the comments are encouraged. Enjoy.
And finally, this isn't fan art, but I think it qualifies as show art and has a place here.