Acrassus or Akrassos () was an ancient Roman and Byzantine-era city in Lydia (modern Turkey). in the Roman province of Asia and Lydia. Apparently, it is the same place that Ptolemy calls Nacrasa or Nakrasa (), placed on the road from Thyatira to Pergamum.
It was in the upper valley of the Caicus River, at or near ðlyaslar, but its exact site is not located.
Acrassus minted its own coins.
Acrassus was also the seat of a bishopric and remains a titular diocese of the Roman Catholic Church in the ecclesiastical province of Sardis. It is named after the ancient city and the current bishop is ÃÂura Dà ¾udà ¾ar.