Banks and their data are integral to the world economy. Unlike other industries, trust in financial institutions have far reaching effects on all sorts of economies, politics and societies. It's for this reason that the stability of banks is closely monitored through analysis, rankings and credit ratings.
CBS Library gives access to some more specialized databases on banks and financial institutions.
Banks Regulatory Database (via WRDS)
Contains five databases providing accounting data for bank holding companies, commercial banks, savings banks, and savings and loans institutions. The source of the data comes from the required regulatory forms filed for supervising purposes.
You can also find data on banks and financial institutions via the financial databases as Eikon, Bloomberg and S&P Capital IQ