In Street Fighter II: The Animated Movie, the end of the movie has Ryu fighting Ken who is under Bison's mind control. Ken eventually comes to and they defeat Bison.
The Movie of Batman Beyond, Return of the Joker, condenses this down to having the badly beat-up Batman merely mutter "... Tim." as his previous Sidekick turned Brainwashed and Crazy is about to murder him. It's just about enough to make Tim kill someone else instead of Batman, but it takes a year of intensive therapy to render poor Tim even partially sane. He's still suffering from after-effects of the brainwashing 40 years later.
In the straight to DVD movie The Invincible Iron Man, Iron Man defeats the Mandarin who takes the form of a ghost that possesses the romantic interest this way. This is a bit anti-climatic as a follow up to the the Fin Fang Foom fight.
Downplayed in Penguins of Madagascar, as it only takes Private to make Mutant Skipper remember the memories they had together to snap him out of it.
The Lazarus Effect Combined with a Cooldown Hug. It works momentarily, but Frank was inwardly doubting she was herself and could be saved. Zoe picks up on it with her telepathy and... it doesn't end well for Frank.
In Lilo & Stitch 2: Stitch Has a Glitch, Lilo pulls one of these on Stitch, when his glitches cause his programming to reverse back to "destructive little monster". A finishing "I'll always love you" appeared to finally made it work.
Alice to Nemesis during their fight in Resident Evil: Apocalypse. She does eventually get through to him, but only after nearly killing him.
Terminator 3: Rise of the Machines has a variation of this overlap with Fighting from the Inside, as John under threat from the reprogrammed T-850, knowing full well that reasoning won't work, starts speaking the Terminator's language, and start to take hold of his mantle at the same time in this exchange:
John Connor: WHAT IS YOUR MISSION?!? Terminator:To ensure the survival of John Connor and Katherine Brewster. John Connor: You are about to FAIL... that mission...
Subverted in From Dusk Till Dawn. When Seth's brother rises as a vampire, Seth threatens to kill the others if they try staking him. Instead, he has the others hold him still so he can do it himself.
The Nutty Professor Dr. Klump's assistant tries to "call him back" from inside the body of his violent alter-ego, Buddy Love. Eventually, Sherman DOES fight back, in a very physical way.
MirrorMask. After Helena has been brainwashed by the Dark Queen (the brainwashing process involves turning her, oddly, into a Goth), Valentine The Fool appears and insists that she's still in there. It doesn't work, but juggling does.
At the end of the filmSpider-Man 2, Peter Parker removes his mask and gives one of these speeches to Otto Octavius/Dr. Octopus, encouraging him to overcome the corrupting influence of his tentacles. This is eventually followed by Octavius exclaiming to the appendages, "Listen to me now!" and reclaiming his own mind.
Peter These things have turned you into something you're not. Don't listen to them.
Briefly invoked in The Amazing Spider-Man as Peter battles the Lizard, who is actually his mentor, Dr. Curt Connors, suffering a Jekyll & Hyde transformation.
Sort of in Serenity, with Mal talking to River: "I've risked my ship and crew on the theory you're an actual person, real and whole, and if that's ain't true, you best shoot me now. [River cocks the pistol she has trained on Mal] ...Or we could talk more." Sort of in that there's no actual fighting, since Mal wouldn't last five seconds. That theme recurs through the whole series and movie, but this is one of the best examples.
In Revenge of the Sith, Obi-Wan tries to reason with Anakin at first, before realizing he has no choice but to fight him on Mustafar.
Luke Skywalker uses this in Return of the Jedi towards his father Darth Vader. See the quote at the top of this page. Vader actually told him that it was too late for him and did take him to the Emperor, but in the end it worked.
The Force Awakens: Han attempts this with his son Ben/Kylo Ren and it looks like it's gonna work until Kylo impales him with his lightsaber while pretending to be giving it to him in surrender.
Halfway through The Cell, when Catherine ends up trapped inside Carl Stargher's mind and transformed into one of his mindless dolls, Novak awakens her by reminding her of the time when her baby brother died in a car crash. Impressively enough, he managed this while Stargher was tearing his intestines out and threading them onto a spit.
Much of RoboCop (1987) centres on this trope, culminating in the final line:
The Old Man: Nice shooting, son. What's your name? RoboCop: ... Murphy.
In Tim Burton's Alice in Wonderland (2010), Alice has a moment like this with the Mad Hatter, though slightly inverted. When the Mad Hatter is making hats for the Red Queen, he seems almost... normal and productive and happy. She then has to remind him that he's making hats for the Red Queen, in which he snaps back to (his) normal and freaks out, and asks Alice if he's gone mad. She tells him yes, he has. And he's satisfied.
In The Chronicles of Riddick, Riddick and Kyra have one. It works, but she gets killed by the Big Bad afterwards.
Briefly and foolishly invoked in the film version of Prisoner Of Azkaban, when Sirius tries to prevent his old friend Remus Lupin from transforming into a werewolf. It doesn't work.
Happens in Pirates of the Caribbean: At World's End when Will has to fight his father Bootstrap Bill, who has been driven mad. Bill snaps out of his insanity after Davy Jones fatally stabs Will.
A standoff of this trope appears at the climax of From Paris with Love, in which Reese posits, Was It All a Lie?? (It wasn't). Finally The Mole comes to. Reese defuses the situation and foils a terrorist plot. Except, so not. Subverted. She can't help herself. Love be damned, he plugs her.
Happens twice in Undercover Brother. When Sista Girl is trying to get the title character to stop acting white, and when UB is trying to get General Boutwell to throw off the effect of the drug he's under the control of and not shoot him.
Optimus Prime after getting corrupted by Quintessa duels Bumblebee in Transformers: The Last Knight. Cade Yeager tries to talk Optimus out of doing so trying to remind Optimus, "This isn't you Prime!" Where Cade fails, Bumblebee succeeds and restores Optimus back to his kind, benevolent self.
Rhodes and Tony Stark's rematch in Iron Man 2is a variation. It is clear that Rhodes is sane throughout the fight. However, the suit was reprogrammed remotely by Vanko, alongside the Hammeroids to cause havoc, meaning they literally have no other choice but to fight.
A brief moment, after Bruce Banner transforms into The Hulk. Thor fights with him to keep him from destroying the Helicarrier (and also to save Natasha). He gives up on trying to reason with Hulk pretty quickly, though.
In the same scene, Natasha unwillingly goes head-to-head with Hawkeye, who is under Loki's control. Eventually a crack to the head from Widow brings Clint back around.
Captain America takes an "I Know You're Somewhere in There Beatdown" in Captain America: The Winter Soldier from the Winter Soldier/"Bucky" Barnes, explicitly refusing to fight him in the climax because he will not hurt the Winter Soldier and wants him to realize the truth before he goes too far.
Subverted in Avengers: Age of Ultron. After the Scarlet Witch sends the Hulk on a rampage, Tony Stark tries to calm him down. Unfortunately this trope only sets off the Hulk's Berserk Button.
Tony: You listening to me? That little witch is messing with your mind. You're stronger than her. You're smarter than her. You're Bruce Banner. [Hulk roars in outrage] Tony: Right... don't mention puny Banner. [Hulk throws a car at him]
Thor does this again with the Hulk in Thor: Ragnarok when they are forced to fight each other in a gladiator match. Thor initially refuses to fight Hulk at all because they're friends, and once he's finally forced to fight back in self-defense, he still holds back and tries to get him to revert back to Banner, using Natasha's "lullaby" and even saying "I know you're in there, Banner". However, he's eventually forced to give up on this and fight Hulk for real when it's clear he won't be reasoned with.
Alex confronts a transformed David this way in An American Werewolf in London. It seems to work, briefly, as he stops growling. Then he leaps for her and the police shoot him dead.
Young Sherlock Holmes. After Chester Cragwitch is affected by a hallucinogenic drug that causes violent and self-destructive actions, Holmes tries to talk him down by reminding him of his name and that he's a banker. It works temporarily, but later he succumbs to the drug again and Watson has to talk him down while he's choking Holmes. The poor man is only stopped when a previously doubtful inspector arrives and knocks him unconscious.
976-EVIL: After Hoax becomes fully possessed, Spike reminds his cousin about their youth to help him fight it. It only partially works, as it gives Hoax just enough time to sacrifice himself.
Species II: After Eve and Patrick transform into their full alien forms to mate, Dr. Laura Baker appeals to Eve's human side. It seems to work, as Eve turns against him but is killed in the process.
In Warcraft (2016), Lothar tries this on Medivh when the latter is possessed by the fel. For a moment, things seem to calm down... and then it gets even worse as Medivh turns One-Winged Angel.
Upgrade: At the climax, and once she's completely at the mercy of STEM, Cortez tries to appeal to Grey by saying that he isn't like this. She's right, because the person she's talking to is no longer Grey and he can't hear her anymore, STEM has taken over completely.
Another variation towards the end of The Titan. Rick Janssen has been transformed into Homo titanien so he can colonize Titan, but the process appears to have driven him mad. The Evilutionary Biologist urges Janssen's wife to inject him with a drug that will lobotomise his memories so he will forget his family and settle peacefully on Titan, the only place he can now survive. She injects him with a harmless saline solution instead.
Ouija Mummy: When being grappled by Chase while he's under the influence of Ahotep the 1st's servant, Paul talks to him to try to break himself free of the influence. He succeeds, and Chase regains control of himself.
