- The Optimus Prime deaths. Each incarnation does die once or twice, and that's once or twice more than most characters who aren't from superhero comics, but you can't say "he's died a million times" unless you treat all Optimuses (Optimi?) as if they were the same guy.
- Ultra Magnus is only remembered by fans for the infamous movie line, "I can't deal with that, now". Not only has it become an internet meme, but it also forever painted Magnus in fans' minds as an arrogant and lazy commander who would rather pass off responsibilities to his subordinates than actually get his own hands dirty. The fact that he's seen coordinating strategies more often than he is executing them doesn't help matters much, but he is more proactive than this misconception paints him as being. On top of that, the original line was said as he was in the middle of trying to pilot a ship that was crashing, so it was less "Who cares?" and more "Kinda busy here!"
- Also, from the Transformers Movie, Ultra Magnus "usurps" leadership of the Autobots to the point of insisting the Matrix be merged with his spark, despite Optimus Prime flat out naming Magnus as his successor, and insists that Magnus take the Matrix - Magnus, for his part, even says he's not worthy of it. "Evidence" of this is shown by the fact that the Matrix only glows in the hands of Hotrod, but because Ultra Magnus is the de facto leader at the moment, everyone just ignores it.
- That's not quite how it goes, if you watch the full movie; Optimus Prime, in his deathbed, flat out names Magnus as his successor, and insists that Magnus take the Matrix - Magnus, for his part, even says he's not worthy of it.
- Remember how G1 Red Alert was always panicky and ultra-paranoid? If so, that makes one of us: In the aptly-named episode "Auto Berserk", when a missile hits him in the face, resulting in brain damage that would have killed him eventually, he starts acting in this manner, to the point of helping Starscream get his hands on a superweapon just to keep the Autobots, whom he believes have turned against him, away. He's fixed later. Fans seem to forget both that he was this way for one episode only due to damage, and quite how dangerous the paranoid schizophrenic Red Alert really was. Even his toy bios go on about his paranoia, as if something we've never witnessed in any episode or comic but the brain-damage situation was in fact his defining trait.
- A mild case of Older Than They Think: Toy bios were written (and often toys released) in advance of the characters turning up in related fiction and sometimes bore little resemblance to how the characters were portrayed in the cartoon or comic (Ratchet is described as a party animal, for example). Red Alert's paranoia was used for his Day in the Limelight episode but treated as a temporary state of affairs and ignored elsewhere.
- Mix-Mix-Mixmaster's Verbal Tic of re-re-repeating the beginning of a sentence... some-some-something he only actually did in one ep-ep-episode ("City of Steel"). Thank-thank-thankfully. Shrapnel, however, really did repeat the last word of every sentence almost every time he appeared, appeared.
- Beast Wars once had a damaged Waspinator think he was Shrapnel... only to start talking like Mixmaster did in "City of Steel".
- Sentinel Prime may be going this way due to Transformers Animated, due to his smug attitude, general disrespect for others, and sometimes morally reprehensible techniques. In later continuities, there are some aspects of it, one of the names Zeta Prime has, suggested by the writer of Exodus is Sentinel Zeta Prime, and demonstrates much of the same behavior. The Sentinel in Dark of the Moon seems to avert this. But then it turns out he's worse than the Animated Sentinel, using both sides of the conflict and murdering Ironhide.
- Hot Rod/Rodimus Prime probably would have been the Replacement Scrappy in any case, given how beloved Optimus was, but he really didn't help his case by being partially responsible for Optimus' death, distracting him at a critical moment, with fans insisting he did it deliberately. But with how it went down, with Optimus failing to finish off Megatron when he has a clear shot and thus giving him the opportunity to grab a hidden gun, while Hot Rod could have done a better job of helping, if he hadn't intervened Optimus would have died anyway.
- In the same movie, there was Soundwave not lifting a finger when Megatron was Thrown Out the Airlock by Starscream, and even veering for the role of leader of the Decepticons straight afterwards, which left something of a tint on his Undying Loyalty persona (which ironically was in full display just beforehand when he carried Megatron into Astrotrain in the first place). This has led to fan interpretations of Soundwave being as ambitious and opportunistic as Starscream (if far more shrewd about it) and only playing a loyal follower until the perfect time comes to usurp his leader.
- Transformers even provides a meta-example: Transformers Animated came to a rather sudden end for various reasons. According to some fans, this means that Hasbro loves canceling things and produces shows, comics, and toys for the sole purpose of abruptly canceling them all. Any series people like is met with comments of "wonder if it'll get to episode/issue 10 before Hasbro pulls the plug on it?" and occasionally people ask whether a toy has been canceled after it's already out.
- An in-Universe example occurs in Animated with Bulkhead continually bringing up the fact that Professor Sumdac was, well, deceived into rebuilding Megatron.
Never Live It Down / Transformers