Manual overrides for valves are disclosed herein. An example apparatus includes an actuator to move a stem of a valve. The actuator includes a housing defining a bore and a piston disposed in the bore. The example apparatus also includes a rod movably coupled to the housing to extend into the bore, and the piston is to be movable via the rod or a fluid to flow into the bore. The example apparatus also includes a lock to hold the rod in a first position on the housing where the rod is to disable a supply of the fluid to the bore.