As a warden, the first shapeshift I got was the form of the grey wolf - but there are other ones, you're right! :)
As a priest, if you go to the warden instructor in your city (Qeynos or Freeport) you can get spells that can turn you into a bee, fae, etc. I have bee and fae, I also got a spell that can turn my groupmates into owlbears... buahahha.
Along with the achievement tree, I recieved shapeshift, which is one spell but can turn me into 3 things - a white wolf, a treant, or a tiger.
So yes, there are other forms, but they need to be bought in a sense ;)