I meant to get these posted before Dia de los Muertos [All Souls Day], but that didn't happen.  Instead, you can marvel at them this year and plan to make your own next time... They would, of course, work as Halloween cookies, but since I was using my 
Mexican Chocolate Cookie dough it seemed only appropriate to wait for November 2nd.  Sometimes decorated cookies don't taste as good as the look, but that cookie is a workhorse and has enough flavor to power through my as-tasty-as-it-gets royal icing. [Royal icing looks great but tastes flatly sweet, even with a goodly amount of almond extract. That's why the flavor of the cookie underneath is so important.]
These were pretty fun to make.  As you fill them, different features appear and I'd intentionally leave "highlights" here and there and I found the emerging characters very entertaining... which is good, because I made a double batch (~80) and it did take a while.  On further consideration, I could have made the cookies twice as thick (1/4") and it probably would have made them even tastier.
You also don't need the fancy cookie cutter.  I have one (that 
I think I got after Halloween one year at Williams-Sonoma) so I use it, but you could do the same technique with a simple oval and get almost the same effect (minus the little teeth).  I have no artistic talent*, so I like guidelines.
Recipe: Royal Icing