The banking password may be about to expire — forever.

Some of the nation’s largest banks, acknowledging that traditional passwords are either too cumbersome or no longer secure, are increasingly using fingerprints, facial scans and other types of biometrics to safeguard accounts.

Millions of customers at Bank of America, JPMorgan Chase and Wells Fargo routinely use fingerprints to log into their bank accounts through their mobile phones. This feature, which some of the largest banks have introduced in the last few months, is enabling a huge share of American banking customers to verify their identities with biometrics. And millions more are expected to opt in as more phones incorporate fingerprint scans.

Other uses of biometrics are also coming online. Wells Fargo lets some customers scan their eyes with their mobile phones to log into corporate accounts and wire millions of dollars. Citigroup can help verify 800,000 of its credit card customers by their voices. USAA, which provides insurance and banking services to members of the military and their families, identifies some of its customers through their facial contours.

Some of the moves reflect concern that so many hundreds of millions of email addresses, phone numbers, Social Security numbers and other personal identifiers have fallen into the hands of criminals, rendering those identifiers increasingly ineffective at protecting accounts. And while thieves could eventually find ways to steal biometric data, banks are convinced they offer more protection.