Enemies that you dread seeing in JRPGs

To clarify, what I mean is enemy encounters that are frustrating to deal with because of their dangerous nature as said enemies are known for causing status ailments, and may have so much HP that it takes a while to bring them down.

Secondly, keep in mind while this is all happening, your own party is in severe danger of biting the dust as sometimes a random encounter in an RPG is so deadly that it could wipe out the entire team if they are not dispatched quickly.

To provide an example, I would like to start off with the infamous Marlboro monster from Final Fantasy 10 as while I haven’t run into one yet, I have heard many stories online about how players lost their entire progress due to those creatures because from what I know is that they use breath attacks that cause various ailments on the party.