Female Pig

There are two known instances of Female Pigs, both appearing in the Angry Birds Seasons episode Hogs and Kisses. 

One has the size of a large pig and wears a pink bow and eye make-up. This pig is seen in the credits of the game and in promotional images, as well as appearing in the game. A plush toy was made of this Female Pig.

The second is the size of a small pig and has a big red bow and only appears in one promotional image.

A cardboard cutout Female Pig wearing a blonde wig is seen in the Angry Birds Bing Videos. This cutout was used by the Birds to get back at the pigs for stealing eggs.