In Which We Talk to a Goblin

In Diagon Alley inside the Wizarding World of Harry Potter, you can actually talk to this goblin banker.

Known as simply "Sir," this goblin will exchange muggle money for wizarding galleons, sickles, and knuts. But he will do so in a very grumpy and snarky fashion. So talk to him all you like, but remember...he's still a goblin. ;-)