The title Comptroller is used by financial directors or auditors of some companies and organisations, particularly public bodies (eg in the UK the head of the National Audit Office is styled Comptroller and Auditor General - an example of a postpositive adjective).
The title is common in the USA, for instance the chief financial officer of New York State is a comptroller. However, the comptrollers themselves and the public they serve have a problem knowing how to pronounce the word correctly (see this article from the New York Times).
It's actually pronounced as if it were written controller. Indeed, the OED says it is an erroneous spelling of controller, which started to be used around the year 1500. In Middle English the term used was counter-roller (the original definition in the OED is 'One who keeps a counter-roll so as to check a treasurer or person in charge of accounts'). Counter was sometimes assumed to be from the word 'count' and then this was transformed into the French equivalent compter.
Read how modern US comptrollers cope with the general confusion about pronunciation here.