This next season I plan to do 'The Lion, The Witch and The Wardrobe.' One of the characters is a centaur (half-man, half-horse). Now I considered just dressing up the actor's legs to look like they were hairy but then I realized that the costume would look a lot like a faun like Mr.Tumnus. So I started to lean towards the puppet-like effect that The Lion King used. But I have no idea about how to go about creating such a thing. Also, if anyone else has done TL,TW+TW or even a show which required a centaur and had a different idea, I'd be glad to hear it!

Another option is to use the old vaudeville "dancing cow" technique and simply have a Second Actor, bent over at the waist, behind your Main Centaur Actor.

You could use your original furry-leg idea for them both and drape the second actor with a horse costume that fit around the hips of your main actor. They could rehearse together to coordinate their movements.

I'm not sure exactly how you would bill the second actor in the program, though. "Centaur's butt?" "Half a Centaur?"   "Good Sport?"

Thsi is not my strong suit, but could you build a fake rear end and put it on wheels? Attach it to the actor by means of a belt.   Granted the back legs wouldn't move, but it would be light and give the illusion.

I just worked on a production of Mary Zimmermann's Argonautica and they had a puppeteer who built a VERY stylized Centaur 'rear end' that the actor attached with a belt (think weightlifting belt or tool belt...something substancial).  The overall look of the puppet was very 'simplistic' as if conjured from a childs imagination.  He (and I forget the puppet designer) used bailing wire as an armature and covered it with gauze and strips of fabric.  I imagine you could do a light paper mache if you want a more realistic approach.  The coolest part was that the back legs pivoted (using elastic and springs) and they were attached to the actors ankles (using velcro cuffs) so that as he walked, the back legs moved back and forth.  To give the actor 'hooves' they created a pair of platform boots to achieve the effect.  If you are lucky there may be some production photos online somewhere.