Not to be confused with that wonderful giant space monster from nowhere, Lavos, whom we rather like for the most part. No no no... This is a Final Fantasy rant.
There are two ineffectual villains that stick out in my mind, the uhhh...final bosses of Final Fantasy 4 and 8. There is probably some issue with Necron in FF9, but I sort of let him go in the sense of "Oh crap, Kuja woke up an Eldritch Abomination lord of death!", which for me keeps in with the theme of the game at least. So...
Zemus/Zeromus - What was ever the point of this villain? The game itself was sort of meh for me as is, and I didn't like the final dungeon at all, but then we have out of nowhere...this old guy that wasn't in the story before, and then I'm suppose to feel threatened by him when he goes from old man to stupidly-named monster of hate? For what reason was this thing there? To my knowledge, other previous game bosses hadn't gone out of nowhere. The writers dropped the ball with this one. Ah, but this is just the icing on the cake. Time for me to reprise an FF8 rant.
Ulti-Frigging-Mecia - Putting aside for the moment that the game mechanics are terrible, the weapons are shit, and the characters are ALL unlikeable...lemme explain why this is one of the worst game antagonists around. You start off with the fact that this ASS comes out of nowhere, GSFFN routine, because it's some sorceress from the future. The backstory of Ultimecia is that she did all of this shit because it was prophesized that SeeD (That's YOUR organization.) will destroy her, despite the fact that she lives in a dark future where they're all dead. The LOGIC behind this is astounding. Because they're all dead in her time period, this must have something to do with the past, SO let's go mess with the past and time travel and compress time so nothing Timey-Wimey can hap- OOPS! The compression of time into one event is what caused her defeat. DOOFUS! So, the ENTIRE PLOT (which is a time loop of her doing) made sure that she essentially killed herself instead of sitting on her ass. Brilliant. And then, there's just the fact that her entire boss battle is stupid. Sorceress or not, there's no way that a frail aging woman can have THAT MUCH stamina in the stand-up fight or recover much while her pet is in play, or gain much by merging with said pet when it AND her should be exhausted at once, or be alive and somehow MORE POWERFUL after exploding. No, sorry, uh-uh, bullshit.
Because, when you get down to it, all the popular FF-villains earned their shit! Chaos was Garland flung back into the Temple of Fiends of the past to become the monster of a closed time loop, thus Chaos. Exodus (X-Death) was originally part of a greater evil that was trying to unleash itself, the story unfolding to reveal that shit. Kefka was a monstrous nihilistic bastard keen on delusions of godhood by taking the power of ancient beings. Sephiroth was basically part of an alien organism trying to devour the planet. SIN (because Yu Yevon is NOT the real boss) was created via false religion and a rather short-sighted bid for power and immortality.