Were the Romans ever defeated, and who defeated them?
yes, romans were defeated by many german tribes
The most famous Roman defeat was Battle of the Teutoburg Forest in 9 AD. Arminius of the German tribe Cherusci defeated Publius Quinctilius Varus' legion. Other famous Roman defeat was Battle of Trebia in 218 BC, where Hannibal Barca (from Carthage) defeated Roman legions. Finally Rome was sacked in 390 BC by Gauls, in 410 AD by Visigoths, in 455 AD by the Vandals and in 546 AD by Ostrogoths.