TOS may refer to:

• Terms of service
• The original series of a particular media, in contrast to a spin-off

• Tosyl, a chemical group
• Gy's sampling theory (abbreviation)

• Star Trek: The Original Series, a science fiction TV series originally known as Star Trek
• Tree of Savior, a multiplayer online role playing game published by IMC Games in 2016
• Town of Salem, a social deduction game published by BlankMediaGames in 2014
• Temple of Shadows, 2004 album by Angra
• T·O·S (Terminate on Sight), 2008 album by G-Unit

• Thoracic outlet syndrome, a medical condition
• Toxic oil syndrome, caused by consuming non-food grade oil

• The Oceanography Society
• Theosophical Order of Service, an international organization
• Temple of Set, an occult society
• Tennessee Ornithological Society
• Trucial Oman Scouts, UK force raised in Oman in 1951
• TV Oita, a Japanese TV station

• TOS-1, a Soviet thermobaric weapon
• Tam o' Shanter (cap)
• Atari TOS (The Operating System, also unofficially known as Tramiel Operating System), computer operating system
• TOS/360, Tape Operating System/360
• Tromsø Airport, Norway, IATA code
• Type of service, a field in the header of IPv4 packets
• Terminal Operating System, controlling cargo movement
• Testament of Solomon, a pseudepigraphical composite text ascribed to King Solomon
• Thinkorswim, an electronic trading platform by TD Ameritrade used to trade financial assets
• Town of Salem, a game under the social deduction genre

• All pages with titles beginning with TOS
• All pages with titles containing TOS
• ToS2 (disambiguation)
• Toos (disambiguation)
• Toss (disambiguation)
• TOC (disambiguation)