Ronald Eaglesham Porter, known professionally as Ron Donachie (born 26 April 1956, Dundee, Scotland), is a Scottish character actor. He attended Madras College in St Andrews and earned an MA (Hons.) in English Literature and Drama from the University of Glasgow in 1979. He is best known for portraying Ser Rodrik Cassel, the steadfast master-at-arms of House Stark, in HBO's Game of Thrones (2011–2012), for his supporting role as Master-at-Arms Thomas King in James Cameron's Titanic (1997), and for voicing DI John Rebus in the BBC Radio 4 dramatisations of Sir Ian Rankin's Rebus detective novels, a role he reprised on stage in Rebus: Long Shadows. He has appeared in over 130 productions across theatre, film, and television since the early 1970s. His filmography includes Comfort and Joy (1984), White Mischief (1987), The Jungle Book (1994, as Sergeant Harley), Fierce Creatures (1997), Titanic (1997), Max Manus: Man of War (2008, as Colonel J.S. Wilson), Filth (2012, as Hector), Sunset Song (2015, as Uncle Tam), Steel Rain (2017, as US Secretary of State Michael Dobbs), Outlaw King (2018, as Robert Wishart, Bishop of Glasgow), Rocketry: The Nambi Effect (2022, as Col. Val Cleaver), and I Swear (2025, as Headmaster Donald Watkins). On television he has appeared in Taggart (1983), The Bill (1984, as DCI Andrew Ross, recurring), Doctor Who (2005), Downton Abbey (2010, as Mr. McCree), Rebus (1999–2000, as Jack Gunner / DCI Wilson), Vera (2011), Silk (2011), Blandings (2013), Waterloo Road (2012, 7 episodes), Karen Pirie (2022), Granite Harbour (2022), and Screw (2022, as Don Carpenter, 12 episodes).