Well, as the Shapeshifter Creature Type no longer exists (It is now a subtype), the shapeshifters will be an even more varied bunch:
First we have the humanoids:
Hengeyokai (OA)
Selkie (FF)
Next we have the Monstrous Humanoids:
Bog Hag (OA)
Doppleganger (MM)
Doppleganger, Ethereal (MM2)
Doppleganger, Greater (Monsters of Faerûn™)
Mamono (OA)
Pterafolk (Monsters of Faerûn™)
Then there are the Outsiders:
Barghest (MM)
Barghest, Greater (MM)
Canomorphs (FF)
Malaugrym (Monsters of Faerûn™)
The Aberrations:
Ghaunadan (Monsters of Faerûn™)
Mimic (MM)
Phasm (MM)
And the rest are usually Magical Beasts:
Aranea (MM)
Dokufu (OA)
Grimalkin (MM2)
Jackalwere (FF)
Also, the Beast of Malar template from Monsters of Faerûn™, and the lycanthrope template from the MM, gives the base creature the shapechange subtype.
Later,