Renly received a full blown supernatural death at the hands of Melisandre's baby smoke monster raising the "anything goes" factor on GoT. He was too soft-hearted to be playing at king, poor dear.
Ned: You understand why I did it. Bran: John said he was a deserter. Ned: But you understand why I had to kill him. Bran: Our way is the old way. Ned: The man who passes the sentence should swing the sword.