Highlander, Jaws and The Matrix.
I've heard True Detective goes on this list.
My possibly controversial candidate would be the rebooted Battlestar Galactica
Definitely both.
True Detectives was brilliant in season 1 and total shit for season 2.
BSG did have a good 2nd season. It fell to bits after that. The mistake it made was making the enemy too empathetic. They worked best when they were evil incarnate. The less said about the last season, and that abysmal finale, the better