Frost Bank is an American bank based in San Antonio that is chartered in Texas, with 155 branches and 1,700 automated teller machines in the state.

It is the primary subsidiary of Cullen/Frost Bankers, Inc., a bank holding company.

Frost Bank was founded in 1868 as a mercantile partnership in San Antonio by Thomas Claiborne Frost, who had served as a lieutenant colonel in the Confederate States Army.

[5][7] In 1983, the bank announced it intended to merge with First City Bancorp of Houston, Texas,[8] however the merger was never completed.

[13] During the financial crisis of 2007–2008, the bank did not accept government assistance via the Troubled Asset Relief Program,[2] but faced with changes in the financial services industry, the bank converted its 113-year-old federal charter into a state charter in June 2012.