Ass Pull: Sayla's involvement in the series often gets this response due to lack of foreshadowing or explanation to her actions. It is heavily suggested that her appearance was meant to foreshadow a role in Mobile Suit Gundam: Char's Counterattack, but as her VA was unavailable for the film, this didn't materialize.
Bizarro Episode: "Prelude ZZ", the very first episode, has no particular plot and consists of a long stream-of-consciousness recap and foreshadowing mixed in with occasional acid trips and mobile suit quizzes.
While the anime version of Glemmy Toto had enough redeeming traits to keep him off this list, the same cannot be said for his manga counterpart, a vicious Smug Snake and Starscream who is bad news from his first appearance to his last. Coldly manipulating Puru, an unstable Child Soldier, into doing his killing for him, Glemmy keeps a small army of brainwashed clones of her as backup for when she inevitably dies on him. He burns down a village to draw out Judau Ashta, has a defecting Puru killed by her Evil Twin Puru-2, and eventually betraysHaman Khan, triggering a devastating Enemy Civil War in the process, as he aims to make himself the dictatorial ruler of both Earth and the colonies, unleashing his entire clone army in the process. Idolising the franchise’s original CM, Gihren Zabi, whose DNA may run in his veins, Glemmy promises to be every bit as brutal a tyrant as he was, and betrays no concern at all for the dozens of little girls who are dying to make his dream a reality.
Ensemble Darkhorse: Elpeo Ple, who is also one of the first lolicon characters in anime history.
Evil Is Sexy: Haman Karn and Chara Soon, though with contrasting styles.
Fanon: A rather popular in its day theory says that Glemy isn't Gihren Zabi's clone, but his bastard child. The whole "clone" deal would be false, for two possible reasons: either Glemy a) claimed to be a clone to to disguise his true heritage as Gihren's child and the other Zabi descendant (aside of his "cousin" Mineva) from enemies; or b) it was a lie that he came up with as a youngster to psychologically protect himself from such a burden, and then he himself came to believe it as he grew up. It does provide for a rather interesting Alternate Character Interpretation, though.
Years before, Yoshiyuki Tomino confirmed in interviews with Animedia and B-Club magazines that Glemy was Gihren's son with an unnamed Newtype woman. He also confirmed that Ple and Ple-Two were "artificial/unnatural twins" whose parents were Gihren and a different Newtype woman, meaning they're half-siblings, which adds a new layer of Squick to those scenes where Ple-Two acts romantic towards Glemy.
Fanon Discontinuity: Fans who were less than happy with ZZ eagerly latched onto the Compilation Movie version of Zeta Gundam, whose ending was incompatible with ZZ, as proof that it had been kicked out of canon. Tomino himself said this wasn't the case, and the Zeta movies were merely another take on the events. This was supported by Gundam Unicorn, which features not only several ZZ mobile suits, but a character closely tied to that series as well.
Hilarious in Hindsight: There's an online quiz out there that lets you construct your wolfkin name by matching your first and last name to two wolf-related words. Due to the word Moon appearing in both lists, it's possible to be named Moon Moon, which has even led to Memetic Mutation.
Speaking of the Moon Moon, a race of people who live on the moon and prefer peace when possible, and the protagonist crossdressing at one point? Sounds familiar.
Haman Khan fits the trope, though her personality is significantly different from Glemmy's. While she's not quite as deceptive as Glemmy, this is mainly stylistic; she's equally skilled at politics and able to effectively play her enemies off against each other. In addition, her strength of will is beyond question; she is willing and more than able to take to the battlefield when it's called for, whether on foot or in a mobile suit, and she once stood down an attacking mobile suit with bladed hands and didn't even blink. She makes it clear that her goal is to bring the Earth Sphere under her jackbooted heel, and while she doesn't win, she outlasts Glemmy's rebellion against her.
Moral Event Horizon: The Dublin Colony Drop serves as one for most of those involved: Haman Khan (who orders its implementation), Mashmyre Cello (who aims it), Rakan Dakharan (who guns down the civilians attempting to flee it), and the Federation officials (who leave their own citizens behind to die in it.)
Nightmare Fuel: Ple and Kamille go utterly batshit when Dublin is destroyed via Colony Drop. The split-second image of Ple, who was not in the best mental health to begin with, spasming in terror is one of the most unnerving images in the entire franchise. At least for some people.
Also, what happens when Haman shoots Leina. Judau, normally a Hot-Blooded kid, completely snaps in the mother of all tranquil furies, with anger and power strong enough to cause Haman to Freak Out! and literally cry in fear and be felt by Newtypes who were far away from the place. (The visualization was a demonic phantom emerging out of him. The last time this happened, it was Dozle Zabidoing it.) That is how massively pissed off he was, and it's scary to see. This scene is probably why some consider Judeau to be the Newtype with the strongest raw power.
Retroactive Recognition: Gundam fans who started with later shows and worked their way backwards might find themselves asking "Why does Dorothy have purple hair?"
The Scrappy: Emily Ounce gets a fair bit of hate because her character does nothing except obsessively pursue Bright despite knowing that he's Happily Married to Mirai (when her subordinate Milly points this out, Emily simply glares daggers at her). This obsessive crush even results in her eventual death, but most fans felt much sorrier for the Anaheim employees who had to put up with her crap and almost got killed alongside her.
Special Effect Failure: When Rasara Moon dies, she's supposed to be crushed by falling debris beforehand, but due to an animation error, the debris lands a few feet away from her, making it look like she just fell on Mondo and died for no reason.
Villain Decay: Yazan. After being the resident Complete Monster of Zeta and miraculously surviving the final battle thereof, he's subjected to repeated embarassment at the hands of the ZZ cast before being forced to leap from a flying mobile suit. With a poncho for a parachute. You could almost feel sorry for him... almost.
Especially considering he manages to kill one more significant member of the Argama crew before the decay sets in.
Fanon tries to explain this away as a combination of oxygen deprivation (after being shot out of his suit at the end of Zeta) and hunger (being forced to live like a bum for a majority of his appearance). That might make his situation A Fate Worse Than Death.
As of The Return of Johnny Ridden, he's gone back to being a bloodthirsty Ace Pilot, so this definitely counts.