User blog comment:Srebak/Who came the closest to ending Luffy?/@comment-4374114-20141103145903

For those of you who chose Magellan and Crocodile, you also need to remember that Ceasar Clown could also have easily finished off Luffy. In his first battle with Luffy, Luffy was completely knocked unconcious, leaving him completely vulnerable more than with Magellan or Crocodile.

Aokiji's first encounter could also be considered a close call as had he touched Luffy after freezing him, Luffy would have died.