Shapeshifters are characters who can change into someone or something else. Obviously, this can only happen on fantasy shows. Some examples include Bewitched, I Dream of Jeannie, Once Upon a Time, the Star Trek shows, Touched by an Angel, Highway to Heaven, and No Ordinary Family.

Supernatural

Red Dwarf
Buffy The Vampire Slayer
Werewolf
Smallville
Manimal

Midnight, Texas
The Vampire Diaries

Animorphs
The Secret World of Alex Mack (she turns into goo)
True Blood

Turbo Teen (Turned into a sports car)

Wolf Lake

The Munsters

Bitten