A method of actuating multiple valves in a well can include applying a pressure cycle to the valves without causing actuation of any of the valves, and then simultaneously reducing pressure applied to the valves, thereby actuating the valves. Another method can include releasing a locking device of each valve which prevents actuation, and then reducing pressure applied to the valves, thereby actuating the valves. A valve can include a port which provides for fluid communication between an exterior and an interior of the valve, a closure member which selectively permits and prevents fluid flow through the port, the closure member permits flow through the port in response to a decrease in a pressure differential from the interior to the exterior of the valve, and a locking device which prevents displacement of the closure member, the locking device being released in response to mechanical force applied to the locking device.