10. Dale's Death
Dale is one of the original characters of the show and in the comics survived quite far into the apocalypse, eventually dying during after he was bitten by a walker. Alongside this he'd also lost his leg to The Hunters. Ouch.
TV Dale is a different story though. After AMC's unfair treatment of Frank Darabont which led to his eventual departure from the show, actor Jeffery DeMunn decided he wanted to leave the show out of respect for Darabont. While it was a shame, DeMunn's loyalty to his friend is commendable. What isn't commendable is how the writers decided he should exit the show.
A walker is able to somehow sneak up on Dale in the middle of an empty field and then overpower him, despite the fact that this is the same walker that couldn't get out of some mud earlier in the episode. It gets worse when the walker is somehow able to tear Dale's stomach wide open, despite being a single weak enemy. While you always have to give the show a bit of leeway with the strength of the undead, it's just a ridiculous chain of events.
This was one of the earliest of AMC's infamous blunders, intertwining corporate meddling with poor writing. If only it was the last.