Oldest Oscar winner for Best Supporting Actress
Who
Peggy Ashcroft
Where
United States (Hollywood)
When
Peggy Ashcroft (UK, 1907–1991) won the Best Actress in a Supporting Role Academy Award for Passage to India (UK/USA 1984) on 25 March 1985 aged 77 years 93 days.

 Name  Born  Film  Won  Age
 Peggy Ashcroft (UK)  22 December 1907  A Passage to India (UK/US 1984)  25 March 1985  77 years 93 days
 Ruth Gordon (USA)  30 October 1896  Rosemary's Baby (USA 1968)  14 April 1969  72 years 166 days
 Margaret Rutherford (UK)  11 May 1892  The V.I.P.s  (UK 1963)  13 April 1964  71 years 338 days
 Helen Hayes (USA)  10 October 1990  Airport (USA 1970)  15 April 1971  70 years 187 days
 Josephone Hull (USA)  3 January 1984  Harvey (USA 1950)  29 March 1951  67 years 85 days