SOS is the international Morse code distress signal  (· · · – – – · · ·). This distress signal was first adopted by the German government in radio regulations effective April 1, 1905, and became the worldwide standard under the second International Radiotelegraphic Convention, which was signed on November 3, 1906, and became effective on July 1, 1908. SOS remained the maritime radio distress signal until 1999, when it was replaced by the Global Maritime Distress and Safety System. SOS is still recognized as a visual distress signal.

SoS can refer to:

• Scotland on Sunday, a Scottish weekly newspaper.
• Son Of Sardaar, a 2012 Indian film.
• "Secret of success", a colloquial phrase with varied interpretations across cultures.
• System of Systems, systems that pool their resources and capabilities together to create a new, more complex system.

Kim Yoo-jin, (born October 16, 1993) better known by his gaming handle sOs, is a Korean professional StarCraft II player. He the first two-time StarCraft II World Championship Series winner, claiming the title in 2013 and 2015. Kim currently plays for Jin Air Green Wings. He is a Protoss player.

Save Outdoor Sculpture! (SOS!) is a community-based effort to identify, document, and conserve outdoor sculpture in the United States. By fostering awareness and appreciation, SOS! aims to advocate proper care of a nationwide public resource.

Södersjukhuset (SÖS) is one of the largest hospitals in Stockholm, Sweden. Constructed between 1937 and 1944, it was designed by architects Hjalmar Cederström and Hermann Imhäuser. Södersjukhuset has the largest emergency department in Scandinavia.