What do shape shifters (stars) look like underneath their human-like facades?  The short answer is that they generally look like beings with animal or insect heads.

Think about the cartoon character the pink panther.  He is a biped with the head of a panther.  Feline shape-shifters are similar, in that they are bipedal animals with the heads of lions, tigers, panthers, or other types of cats.  Unlike the pink panther, they are not cartoon characters, and they are not pink.

There are also shape shifters who look like dogs, wolves, apes, or bears.  There are shape shifters who look like birds.  There are reptilians who look like lizard people.  There are beings with toad or frog heads.  There are beings who look like spiders.  There are shape shifters with fish heads.  And there are shape-shifter beings who have heads that look like ants, bees, cockroaches, or other insects.

In summary, there are many species of shape shifters who come in many different shapes and sizes, but in public, people see them in their human-looking forms.  Most humans have no idea that shape shifters even exist.