SIG Sauer [ɛs iː ɡeː ˈzaʊ̯ɐ] is the brand name used by several sister companies involved in the design and manufacture of firearms. The original company was Schweizerische Waggon Fabrik (SWF), later Schweizerische Industrie Gesellschaft (SIG) but it then went through several selloffs and the SIG Sauer brand is now spread over several companies. The original SIG is now known as SIG Combibloc Group and no longer has any firearms business.

• The German company is SIG Sauer GmbH & Co. KG. It was formed in 1976 as a partnership between Schweizerische Industrie Gesellschaft (SIG) of Switzerland and J.P. Sauer & Sohn of Germany.

• The Swiss company is Sig Sauer AG. Its predecessor SIG Arms AG was sold to L&O Holding in western Germany and was first renamed SAN Swiss Arms AG — commonly known as Swiss Arms — and in late 2019 was further renamed SIG Sauer AG.

• The American company is SIG Sauer, Inc. Its predecessor SIGARMS was founded in Virginia in 1985 to import and distribute SIG Sauer firearms into the United States: Its headquarters were moved to New Hampshire in 1990. This company was renamed SIG Sauer, Inc. in 2007, and since 2000 is organizationally separate from SIG Sauer GmbH.