First, a word of warning: the German term "controller" has certainly been borrowed from English. However, like many loanwords, it is ambiguous and is used differently. If you are a controller in a German company, your equivalent in the USA or UK is a management accountant. A financial controller in both countries handles the cash flow of the company and has a similar task repertoire to a bookkeeper. A management accountant, on the other hand, provides the executive layer of a company with accounting data in order to inform decisions on how to optimize the running of the company.