Dynamic/Villainous On-Screen Brother/Sister Duo died within a year of each other

Diana Rigg [British actress who played Lady Valentine] died just last year of cancer. She was 82.
Charles Grodin [American actor who played the role of Nicky Valentine] he just passed away; he was 86. Possibly by old age.

Rest In Peace To Them Both.

Diana Rigg 1938-2020
Charles Grodin 1935-2021