S7 Airlines, legally PJSC Siberia Airlines (Russian: ПАО «Авиакомпания "Сибирь"» "PАО Aviakompania Sibir"), is a lowcost airline headquartered in Ob, Novosibirsk Oblast, Russia, with offices in Moscow. As of 2008, it was Russia's biggest domestic airline. Its main bases are Domodedovo International Airport and Tolmachevo Airport.

What is now S7 Airlines started in 1957 as "the Tolmachevo united squadron" of the General Directorate of Civil Aviation of the USSR. After the Soviet Union disintegration and during 1990's Russian economic reforms a state-run "Siberia Airlines" was created based on the squadron in 1992 and later privatized in 1994. The same year Siberia was assigned an IATA airline code. Siberia Airlines was rebranded S7 Airlines in 2006.

In 1997, Siberia Airlines tried to buy Vnukovo Airlines, to make Moscow its next main hub, but this didn't eventuate.

After the 1998 Russian financial crisis, Vnukovo Airlines was heading towards bankruptcy, and Siberia Airlines advised it to merge, but Vnukovo refused. In 1999, Siberia Airlines signed a document for the Vnukovo Airlines take-over, in the event the airline ceased operations due to insolvency.

S7 Airlines began merging with Vnukovo Airlines in 2001. S7 Airlines had acquired all the aircraft from Vnukovo Airlines including Tupolev Tu-154, Tupolev Tu-204-100 and Ilyushin Il-86.

In 2001, the airline absorbed Baikal Airlines and then in 2004, the airline absorbed Chelyabinsk Airlines and Enkor. In 2002, S7 Airlines (then known as Siberia Airlines) painted all Vnukovo Airlines fleet with Siberia Airlines livery and the airline began its service from Moscow-Vnukovo, but after some time it shifted all the flights, including the charters from Moscow-Sheremetyevo, to Moscow-Domodedovo.

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