Out of the ones played, I've always found Emerald Weapon of FF7 to be the scariest. He just looks sooooo creepy.
Happily exploring underwater with that great music......then this big green thing that looks like it has an exhaust pipe comes into view. Eeeep!
Getting the Ancient's Key and turning to go......arrrgh! there it is again!
Leaving the sunken Gelnika after some successful plundering......ahhhhhh! this damn things following me! mayday! mayday!
I naively went into battle with him as a newbie.....and getting slaughtered so quickly...the mental scars have never healed (sniff)
How about you....which FF Weapon scares you the most? Visually, or battle wise?