@gailcalled my mother, my SO and I are hooked on Downton Abbey! Maggie Smith is a true treasure!
I’m also going to suggest:
Morgan Freeman, especially in Shawshank Redemption
Alan Rickman in the Harry Potter series as well as Sense and Sensibility, Snow Cake and Dark Harbor and The Barchester Chronicles
Emma Thompson in Sense and Sensibility and Love Actually
Kate Blanchett in Notes on a Scandal
Judy Densch in Notes on a Scandal, Masterpiece Classic: Cranford, Mrs. Henderson Presents, Mrs. Brown
Anthony Hopkins in Silence of the Lambs, Magic, The World’s Fastest Indian, Nixon, Remains of the Day, and Shadowlands
Tony Shaloub in Big Night and Monk
Meryl Streep in Julie and Julia and It’s Complicated (she’s been in tons of marvelous films, but these 2 are my favorites)
Patrick Stewart in Star Trek The Next Generation and A Christmas Carol
Benedict Cumberbatch in Sherlock
Edward Norton in the Painted Veil and the Illusionist
James McAvoy in Becoming Jane