Adaptation Displacement: There are people who aren't aware there were Gundam series before this one, though this attitude was mostly prevalent when Wing was new to foreign shores and mostly justified as it was the first official widespread western release of any gundam show.
Americans Hate Tingle: Fan opinion of Relena is split in America, while in Japan, she would often appear on the Gundam Ace "Top 30 Females" monthly ranking, and she is the only female Gundam Wing character (so far) to appear on the list, not to mention ranking #21 on Newtype's list of Top 30 Female Characters of the 1990s, as well as spawning many close copies (and not just in Gundam either).
Awesome Music/Ear Worm: White Reflection from the OST for "Endless Waltz" has a pulse pounding track and vocals. If that doesn't get your blood pumping, it's doubtful anything else will. Also, good luck trying to get it out of your head.
Relena is THE poster child for Broken Bases in Gundam Wing (if not the entire franchise itself) though the majority of it is caused by shipping. And if it's not because of the shipping, it's because some fans ignore (or at least refuse to acknowledge) her Character Development throughout the series. Again, this mainly applies to American audiences.
Wufei has two camps: one that seems him as a Jerk Ass and being seen as a Hypocrite who killed sleeping soldiers despite his honour/justice proclaimations and refusal to beat up weaker opponents. The other camp respect him more for it, for sacrificing his own personal honor for the greater good.
Big Lipped Alligator Moment: The first ending is a song about a Type A Tsundere, as Relena glares at the camera and annoys various animals on safari. Relena's presence is basically the most this sequence has to do with the events of the actual show.
There are essentially three bases involved: the old guard mecha fans who think the show is schlocky bullshit starring invincible prettyboys (or at best, So Okay, It's Average), the Yaoi Fangirl crowd who only cares about the cute guys and nothing else from the show, and the actual Wing fans who are tired of both of the above and just want to enjoy their show in peace.
While thankfully mostly a thing of the past now, debates about whether the original TV mobile suit designs or the revised designs by Katoki as seen in Endless Waltz were better could get downright NASTY.
Complete Monster: While perhaps the lightest work of the series, that can't be said about the Romefeller Foundation's Chief Engineer, KenTsubarov. A loud, abrasive jerkass, with No Indoor Voice and a Hair-Trigger Temper, Tsubarov eventually reveals himself as a Blood Knight by proxy who enjoys watching his Mobile Dolls slaughter enemy soldiers, supporting Duke Dermailin the hopes that the latter will trigger an enormous war for his Dolls to show off their skills. When Lady Une, a major supporter of his project, reveals that she likes the automated Mobile Dolls because they will cut down on human casualties, Tsubarov turns on her, as he wants his Dolls to have the chance to kill people, and plenty of them. When the White Fang rebellion reaches the colonies, Tsubarov betrays Une, seizes control of the colonies, attempts to murder the captive Gundam pilots by cutting off their oxygen, and guns Une down when she tries to interfere. He proceeds to improve his Dolls, and begins construction of the Kill Sat/BattlestarLibra for his boss. When the rebels come for him, Tsubarov finally snaps, undergoes a huge Villainous Breakdown, and turns his Dolls loose on the civillian population, ranting like a madman the entire time about how, through them, he will achieve invincibility.
Crowning Music of Awesome: The soundtrack contains quite a few, and even those who don't like the rest of the series will concede that it has an awesome soundtrack. It helps that the whole thing, minus openings and endings, was done by Kou Otani, the award-winning composer for Shadow of the Colossus.
Two-Mix performs the opening and ending themes. That can't be anything but awesome.
Die for Our Ship: Relena is the most infamous case of character bashing ever in Anime fandoms, and a strong contender for all fandoms. This also happens to her rival Dorothy, Duo's best friend Hilde and Chang Wufei, but it is much rarer.
Duo is one of the most popular characters in the series, especially in the West. In the semi-official Gundam Ace "Top 30 Male Characters" poll in Japan, as well as the "Top 30 Male Characters of the 90s" poll in the March 2010 issue of Newtype magazine, he is the second most popular male Gundam Wing character (#21 in the Newtype poll), after Heero Yuy. Also, he was voted the Best Male Character in Animage's 1995 Anime Grand Prix Awards, and was voted the 3rd Best Male Character the following year.
Episode Zero features a young girl roughly Trowa's age named Midii Une; Fanon often tries to draw a connection between her and Lady, despite the fact that Word of God says there is none (Midii references a father and brothers, but no female relatives). Rather, Word of God says that the connection 'will remain a secret forever'. In other words, there is one, but they'll never tell.
Fan Nickname: Hilde is ofttimes referred to as "Mini-Noin", because she looks almost exactly like her, except younger. Ironically, Episode Zero shows us a 12-year-old Noin, who looks exactly like Hilde in her OZ cadet uniform, only more stoic and formal.
Fanon Discontinuity: Frozen Teardrop is basically official Fan Fiction. Even worse when you consider that it was written by the series' head writer.
Problems with Frozen Teardrop include but are not limited to:
Every character looking exactly the same, including Heero Yuy the pacifist who looks exactly like the completely unrelated Heero Yuy the Gundam pilot
Pretty much everyone is revealed to be a clone of someone
Every character being related, case-in-point Heero is distantly related to Trant Clark of all people
The ancestors of each character being revealed as being total assholes, if not worse.
Excessive and unnecessary detailing of back story, trampling over the well-received Episode Zero (believe it or not part of the appeal of the Gundam pilots was their mystique.)
Taking the number-naming convention to ridiculous extremes (believe it or not, many of Wing's original characters weren't named for numbers)
A main plot and set-up befitting a poorly written fan-fiction (see above and Harsher in Hindsight below).
While not declared fanon discontinuity, the Glory of the Losers manga, a retelling of the series with relevant side-stories added to the narrative, suffers the same problems. While it is beautifully illustrated and incorporates the much-loved Katoki redesigns, it also has horrible structural problems (shoe-horning in backstory/flashback at inappropriate points) and retcons a fair amount of the original series material (ex: Heero apparently killed Darlian, not Oz). Not to mention including material from the already much hated Frozen Teardrop.
Foe Yay: Dorothy's obsessive passes with Heero and Quatre on occasion (not even counting her snarky interactions with Relena) remain rife with suspicion to this day.
The Fourth Wall Will Not Protect You: In the series and Super Robot Wars games the final attack of Gundam Deathscythe Hell show your screen with interference until it disappears, then reappears higher and destroys you, then more interference appear showing only a shadow of Gundam.
Gateway Series: While not the first Gundam series released in America, Wing was the first to gain a large audience, and is the main reason more of the franchise made its way over to the West in the early/mid-2000s.
Germans Love David Hasselhoff: For being the Gateway Series for the Gundam franchise in the United States, and being considered less popular then the likes of Seed and the UC in Japan... by a considerable margin. It isn't Wing is disliked, but rather that the Universal Century and Cosmic Era timelines have much stronger and more fanatical fanbases. A 2014 poll, however, still placed Wing as Japan's 5th favorite Gundam series.
At least initially, the Japanese fans (especially the women) despised Quatre, while he's one of the more popular characters in the West.
This trope actually gets acknowledged in some sources; for example, Gundam Extreme Vs. Full Boost's encyclopedia entry for Wing notes that it was the first Gundam show to air in America and remarks on its international success.
Zechs: Don't go getting too attached, or parting will hurt. Noin: I appreciate you being so concerned, but my soldiers aren't ever going to be killed in battle.
Of course they're not, Noin. Because Wufei's going to kill them in their bunks, first.
Many a fanfic has had Relena go evil, usually to facilitate killing her off and setting Heero with Duo. In Frozen Teardrop, she actually is brainwashed into evil - and it's implied that she caused her own brother's her brother's stand-in's death thanks to it.
In a Real Life example, there's a lot of Pakistanis out there who are probably wishing more people took Trieze's message about the dangers of using robots as tools of genocide seriously.
Speaking of Real Life, the controversy over "Mobile Dolls" and the meaning of unmanned combat vehicles takes on a whole new light 15+ years after this show's release, when drones and robotic unmanned combat vehicles are just beginning to enter the battlefield.
The entire mission of the Gundam Pilots was to prevent their colonies from being used by Dekim to crash into the earth. Their next show, shows what happens if the real Operation Meteor went the way it was intended.
Zechs after the series. Noin's trust in him wasn't helping. Indeed, he was back from the grave in the movie. He even claims he was dead when asked.
Also applies to his MS: The novelization ends by stating the whereabouts of the Gundams and mentions Epyon is at the bottom of the ocean. Frozen Teardrop follows up on this by having Zechs recover it and upgrade it into Epyon II.
Memetic Loser: The Leo mobile suit is considered to be the worst mobile suit in the entire Gundam meta-series. The repeated stock footage of Leos getting destroyed and an instance when a pair of Leos explode from a missed buster rifle shot haven't helped. While its specs aren't terrible, it has never been upgraded, further cementing its reputation as a disposable low-level mook that blows up if so much as sneezed on.
Mis-blamed: For years, actor Mark Hildreth was blasted by fans for making Heero sound stiff and emotionless in the dub. Then, at a convention, he said he was told to act that way. Possibly because of the backlash, he has never been called back to play Heero in other media (though he has said he'd be happy to if given the chance).
The dub, being your typical cheesy 90's dub, has its fair share of moments, including General Septum's downright cartoonishly angry voice. (Even when he thanks someone for holding the door for him he sounds outraged.)
Zechs riding the Tallgeese into battle while saying "But I can't falter with the Sanc Kingdom right in front of my eyeeees!" in his best Jack Nicholson voice. Ditto for infamous yell of fooooolllls while destroying a cancer mobile suit.
Despite being a more "serious" show, it almost seems like the franchise is still shaking off the effects of the previous entry, what with the rosepetal bubblebaths and Made of Iron Heero and all... which, intentional or not, is often hilarious.
General Septum's voice.
"Heeeeeeeroooo! I'm right here, so come and KILL ME!"
The way some fans act, you'd think Wufei's entire vocabulary consisted of four words: "justice", "evil", "woman", and "Nataku".
People can't get over Relena's bizarre behavior towards Heero, either. Yes, it was strange. She also stopped acting like that fairly early in the series, acknowledged it was not the best move (she was hurting badly over the loss of her adoptive dad and followed Heero to try coping with her inner pain), and by the end of the TV series she made a point about how she won't follow him anymore and HE will have to chase after her instead if he wants to see her.
Quatre was briefly driven insane by the ZERO system and went on a berserk rampage that nearly killed Trowa. Granted, most of the damage was limited to an evacuated colony, and Quatre was suffering from grief over the death of his father and betrayal by his colony. Still many in both the fandom and in-universe characters like Catherine can't forget about his decision even after he successfully atoned.
A non-character example would be the Leo suit. The Leo suit will always be remembered by fans as a crappy piece of junk that would be destroyed if so much as sneezed on.
Much of the Leo's poor reputation stems from it's lack of real accomplishments. It is always on the receiving end of a Curb-Stomp Battle and hasn't been successfully used by the main characters, unlike the Taurus or Aries. While the Gundam series has plenty of lowly Mecha-Mooks that serve as Cannon Fodder, many like the Zaku and Tieren models were at least upgraded into Ace Custom variants piloted by an Ace PilotEnsemble Darkhorse.
Nightmare Fuel: In particular, some of the things that the ZERO system is capable of doing to its pilots' heads.
Portmanteau Couple Name: One of the more famous examples in Anime fandom, Wing combines this with the Numerical Theme Naming; hence, 1x2 means Heero/Duo; since most of the show's women don't fall under the theme, they're identified by initial (1xR = Heero/Relena).
The order in which the names are listed is important too. Whoever is listed first is the initiator or "aggressor" of the relationship, while the listing of XxYxX (as in 1xRx1) means both partners are equally interested. Certain listings indicate shifts in personalities; for example, 2x1 means a moody Duo with a happy Heero. Don't think about it too hardor you'll go cross-eyed.'
Real Women Never Wear Dresses: If people don't bash Relena for "taking Heero away from Duo", she's bashed for being unapologetically girly or having a pink limo (which her parents gave her, so it's not like she can choose the color).
Saying that Relena gets this is like saying "the sun is bright"; the bare statement of fact simply doesn't do it justice.
The Scrappy: Head writer Sumizawa revealed in an interview that Quatre, of all people, was rather unpopular during the show's run, with Japanese girls nicknaming him "The Space Heart Jerk".
Ship-to-Ship Combat: Yaoi and Het fans can get very... touchy about their pairings of choice. The main war is over Heero x Duo vs. Heero x Relena fans.
You don't even need to bring up Heero/Relena in front of Heero/Duo fans. If you ask "Hey, who tops? Heero or Duo?" you can have a really "nice" flame war.
Squick: The first time Heero uses the ZERO System on the Epyon it causes him to throw up. Inside his pilot helmet. Twice!
Tear Jerker: No one can say they didn't at least get a little misty-eyed during Gundam Sandrock's death scene.
Uncanny Valley: Mariemaia during all but the last act of Endless Waltz speaks in a far too even a tone regardless of what she's actually saying, and emotes pretty much once...at entirely the wrong moment to be doing the kind of emoting she does. The result is rather creepy and can fall squarely into this trope.
Values Resonance: A huge part of the show is the philosophical debate over whether or not Mobile Dolls — automated mobile suits — are ethical. It makes for interesting watching in the era of remote drone strikes.
Woolseyism: In an early episode, Duo refers to Relena as "Ojou-san", which is the proper way to address a young woman of high social status (though he may have just been flirting). In the US dub, he instead calls her "good-looking", which is more obvious flirting and gets around the fact that there's no English term that quite matches the original.