Prepare cake mix as directed on package, adding vanilla to batter.
Bake as directed on package for cupcakes. Cool cupcakes on wire rack.
Divide frosting in half. Use half of the frosting to spread a thin layer on cupcakes. Tint remaining frosting black with 1/2 teaspoon black food color. Spoon frosting into small resealable plastic bag. Snip a small corner from bag. Pipe frosting in the shape of a widow’s peak for the vampire’s head. Pipe a line of frosting for the mouth. Use jelly beans for the eyes and gummy candies, cut into triangles, for the fangs.