Debt Buyers suing in the name of the creditor, legal?

by Bill
(Osage, Iowa)

I'm wondering why a debt collector, who buys the defaulted (charged off) debt from the creditor for pennies on the dollar, can say he is collecting this debt for the creditor? If he bought this at a bargain price, he should sue you in his name over a debt he bought. If a creditor is listed on the summons to apparent in court, isn't that fraud? The collector is NOT the creditor and he does not represent the creditor.

I can understand if a collector sues me, it will be him vs me, but when he tells the court that "his client", the creditor, isn't that a lie?

Thank you