Awesome pixel-art sets! Just following you and viewing your creations. Always looking for Zombie stuff... and this seem to be a good start.
May I suggest some additional and useful animations: very slow walk, maybe limping, dragging one foot or leg (classic style, Night of the living dead speed), uncontrolled running (28days style ;) ) , grabbing hands/arms only (like reaching out of the ground/grave) , climbing out of the ground/grave.
Thanks in advance, best regards!