Ooh, I got a couple more here:
This thing. It's a tree. A damn tree. But it was always one of those "ARGH, not one of those things again! Kill it! Kill it fast!! !". The main thing that these aggravating things did was explode. Violently. Typically, it did a colossal amount of damage, very frequently enough to obliterate your entire party. Your one chance at not being a puddle of goo was the game's funky "wind-down" mechanic, as I call it. Your HP value didnt just instantly change when a character took damage; it would take a bit of time to sorta roll to the appropriate number. It did this fairly fast, but the further it had to go, the longer it took. A character was not considered dead until it actually reached zero.... so if you took your turns and did your actions fast enough, and ended the battle before it hit bottom, it would freeze, and instead of dying you would now be left with that much health, and the battle would be won. Which meant killing the hell outta anything else in the battle REALLY QUICKLY. Chances are, when the tree popped, you only had about a minute or two before those counters reached bottom.
It caused alot of panicky moments in that game overall. There were multiple versions of the horrid thing, too.
And this.... if you know what this is from, you deserve a sack of cookies. Bloody strange game.
It's memorable because.... well just look at it! It's an evil dog head that sticks out of the ground for no apparent reason! Easily one of the RPG monsters I have a strong memory of.