Who conquered rome?
King Alaric. The Sack of Rome occurred on 24 August 410. The city was attacked by the Visigoths led by King Alaric. At that time, Rome was no longer the capital of the Western Roman Empire, having been replaced in that position first by Mediolanum in 286 and then by Ravenna in 402.
If I exclude Roman armies, at the dawn of recorded history in the region, Rome was ruled by the Etruscans. Rome next fell briefly to the Gauls in 390 BCE. Alaric sacked Rome (see other answer) in 410 AD. the Vandals in 455 and finally Ordovacar of the Heruli ended Roman sovereignty in 476.