QOS or Qos could refer to one of several things:
- Quality of service in computer network trafficking refers to resource reservation control mechanisms
- Quantum of Solace, a number of works related to Ian Fleming's James Bond:
- The original short story
- A 2008 cinematic production with a plot written by Michael G. Wilson
- Quarterdeck Office Systems, a software company that is now part of Symantec
- Queen of the South F.C., a professional association football club formed and in existence since 1919 in Dumfries, Scotland, often colloquially abbreviated to QoS (as listed on the club badge)
- Queensland Ornithological Society, a state birding organisation in Australia
- The Edomite god Kaus