One of those annoying situations where she is billed as "star of the Harry Potter films and Downton Abbey". That doesn't even begin to scratch the surface of her talent and career.
She is one of only 15 women who have achieved the US Triple Crown of Academy (film) Emmy (TV) and Tony (stage). And she has won more awards in these three categories (total) than anyone else in that club.
She has acted with Laurence Olivier, Michael Gambon, Derek Jacobi, Richard Burton, Orson Welles, Elizabeth Taylor, David Niven, Peter Ustinov, Bette Davies and pretty much anyone over the last 70 years who was an acting legend. And was the equal of any of them.