This a mechanism that I designed for a character that would walk towards you then turn around and walk away then turn back towards you and then continue walking.
The top part of the sketch shows a top down view with the center electrified rail that also acted as a guide. The center rail would have a pinch roller motor that would be using friction to move the figure forward.
The ends of the rail are rounded so when it reaches the end it just swivels and then begins to travel around and back down the rail like the arrows indicate.
The figure on top of this would probably have to be light and there might need to be some tweaks to the width of the disk that the figure rides on to get it just right. I imagine a ghost with a flowing dress would look amazing on this thing or if you want to make it awesome for a zombie you could add some swivel action and make the waist down blocked from vision and add some bumps to have the end of the base to roll over for a good walking hobbling action.