batch find and replace/renaming

Hello,

I have a long list of company names that I would like to anonymise/rename. In a column I might have:

BMW
BMW
BMW
Ford
Rolls Royce
Rolls Royce

Is it possible to automatically replace everything in one go - with unique names, so that all BMWs might become "A" or "Company A" etc. Or will I have to do it company by company - there are hundreds of them.

Many thanks in advance,

Adam