Hydraulic starters are alternative starting systems, most commonly used in the marine, oil and gas, mining and construction industries. They provide a manner in which to start a diesel or propulsion engine, often when no other power source is readily available. This situation, where there is no local power available with the main engine off, is sometimes called a blacklight system—or the act of starting the engine in this manner is referred to as performing a black start.

These starters, which are miniature, self-contained hydraulic systems, use a pre-charged accumulator to deliver hydraulic power to operate the starter and start the engine. Once the engine is running, a PTO-driven pump will recharge the accumulator. If the accumulator has been exhausted and an engine start is desired, many systems will include a hand pump, to allow the operator to charge the accumulator manually, so as to perform a start. In this way, the operators are never without the capability to start a diesel engine or a gas engine.

In some cases, where there is auxiliary power available and/or if an explosion-proof situation is present, air-operated starters will be used instead.

In many of these systems, due to the nature of the environment they are being use in, biodegradable hydraulic oil must be used, in case of accidental spillage.