From today, Abbey and Bradford & Bingley will become Santander as the Spanish banking group rebrands its British businesses.
1,000 branches are changing to the new name today.
Alliance & Leicester's 300 branches will also be rebranded by the end of the year.
The new combined bank will have around 25 million UK customers, and the company says it's good news for if you're one of them, as you will eventually have access to three times as many branches.
Santander says it means they’ll also be able to offer the full range of its products across the whole UK network.