Title kinda says it all. What DC thing had an ending you didn’t see coming.
I jumped out of my seat in shock and excitement when I saw the Comedian’s button at the end of Rebirth #1, so that really sticks out as a surprise ending. Also had a similar reaction when Martian Manhunter revealed himself at the end of Supergirl 1x07
The last scene of “The Late Mr. Kent” in Superman: The Animated Series, where a death row convict realizes Clark’s secret at the moment he’s killed. I never expected the show to go there.