Ok, this time it's the reverse scenario: clearly Supporting roles that were pushed up to Lead for whatever reason.
This one was a bit harder for me to formulate, as there are so many borderline cases and thus many I left off the list (I debated long and hard about whether to include Frances McDormand in Fargo, but since I already had somebody from 1996, I decided not to include her). Obviously, such a list could also include Eleanor Parker in Detective Story, Rex Harrison in Cleopatra, Peter Finch in Network, etc., etc.
Also, as you can see, this scenario occurs far more regularly in the Actress category than it does in the Actor category, indicative of the paucity of good Lead roles for women.