This is a paid asset, but now you can download Zombie Motions Pack 1 Free.
Detail this asset from Unity Store: Original Link
Zombie Motion v1.3
This asset is composed of various 47 high-quality motion capture animations needed for game development.
These 47 animations can be utilized for expressing diverse Zombie in making your game such as a large crowd
Animation Clips consist of all looping animation Mecanim compatible.
1.3 Ver. Add to Root Motion