Has anyone been knighted after they died?
I googled “knighted posthumously” and came up with Robert Falcon Scott and Murray William James Bourchier so it is indeed possible.
oops fudged the URL in the first link, Robert Falcon Scott
I would think they would have to skip the “Rise, Sir knight.” part.
Scott was never knighted, posthumously or otherwise. Rather it was that his wife was granted by royal warrant the style, rank and precedence of the widow of a KCB.
The Wikipedia entries on the two of them actually gets this right, with the discussions about the later providing more information, including a cite that leads back ultimately to the entry on Kathleen Scott’s second husband in the Complete Peerage.
They’d add: “Or just stay where you are. It’s cool. Whichever is most comfortable.”