B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Total 3500
Situational Awareness; Time Pressure
Aircraft Equipment Problem Less Severe
Flight Crew Returned To Departure Airport
Aircraft
The aircraft indicated we lost all our system A quantity hydraulic fluid.  We ran the checklist. I felt the safest course of action was to return to [the airport]. We landed with no further issues.
B737 pilot reported a complete loss of System A hydraulic fluid.