In creative works, one of the common rules is a character who either has or is diagnosed early on with a terminal condition will be dead at the end (i.e., Chekhov’s Cough). However, this rule is not a constant since there are times a doomed character will get a temporary stay of execution from his or her creator. This thread is about those exceptions.
The first example that comes my mind is the lesser-known Burt Reynolds movie, The End. Burt’s character, a crooked real estate agent, is diagnosed with an unspecified incurable illness in the opening scene. He’s still running around when the credits roll.