Dame Maggie Smith, who retired at 89, was renowned for her roles in Shaw, Ibsen, Stoppard, and Shakespeare, including Desdemona in “Othello” and Violet Crawley in “Downton Abbey.” Known for her humor about always being in corsets and wigs, she also portrayed Professor McGonagall in “Harry Potter,” Mother Superior in “Sister Act,” and won an Oscar for “The Prime of Miss Jean Brodie.” In “The Lady in the Van,” she played a homeless woman living in a van. Her career spanned seven decades, marked by upper-crust diction and working-class tenacity.