Lindsay Vere Duncan, CBE (born November 7, 1950) is a Scottish stage and television actress. She is the recipient of three BAFTA nominations and one Scottish BAFTA nomination, as well as two Olivier Awards and a Tony Award for her work on stage. She has starred in several plays by Harold Pinter. Duncan's film credits include Prick Up Your Ears (1987), The Reflecting Skin (1990), City Hall (1996), An Ideal Husband, Star Wars: Episode I – The Phantom Menace, Mansfield Park (all 1999), Under the Tuscan Sun, AfterLife (both 2003), Starter for 10 (2006), Tim Burton's Alice in Wonderland (2010), About Time (2013), Birdman (2014), and Blackbird (2019).

Outside of stage and film, Duncan appeared as Barbara Douglas in Alan Bleasdale's critically acclaimed G.B.H. (1991), Servilia of the Junii on the HBO historical drama series Rome (2005–2007), Adelaide Brooke in the Doctor Who special "The Waters of Mars" (2009), Anjelica Hayden-Hoyle in the BBC Two miniseries The Honourable Woman (2014), and Lady Smallwood on BBC One's Sherlock (2014–2017). She also portrayed Elizabeth Longford and Margaret Thatcher in the television films Longford (2006) and Margaret (2009), respectively.