MV Orion (formerly MV Saturn, Scottish Gaelic: Satharn, and MV Orcadia) is a ro-ro passenger and vehicle ferry. Saturn was operated by Caledonian MacBrayne in the Firth of Clyde in Scotland between 1978 and 2011, for the first decade of her career on the Rothesay crossing. Later, she also saw service on the Dunoon and Brodick crossings, as well as on short cruises around the Clyde.