Times where being possessed causes the vessel to transform in Video Games.
- In Diablo, this happens to Prince Albrecht when he is possessed by Diablo, and following the hero's sticking of Diablo's soulstone into his own head, he winds up possessed as well, and becomes the new Diablo in Diablo II. In Diablo III, Leah suffers the same fate when her own mother, who had her with the Diablo-possessed Aidan, uses the Black Soulstone, with all seven Great Evils inside, to turn her into a vessel for Diablo's rebirth as the Prime Evil. She transforms into Diablo when Imperius tries to incinerate her to draw Diablo's true form out.
- Divinity: Original Sin II: Lohse gains a greyish pallor, Tainted Veins, and Black Eyes of Evil when her demonic Enemy Within is affecting her, though the ordinary appearance of the demon's primary host suggests that it can suppress the physical changes at least sometimes.
- In Doom³ (and, quite possibly, the old Doom games) demonic possession turns people into zombies.
- Dragon Age:
- This eventually happens to anyone possessed by a demon.
- If a Darkspawn Archdemon is killed by anyone but a Grey Warden, its soul will simply jump to the nearest Darkspawn. Corypheus (second and third game spoilers) has a similar power, what with being one of the Magisters who became the first Darkspawn. Unlike an Archdemon, however, he can posses Wardens and survive the process.
- Grim Dawn: This is what makes living creatures possessed by the Aetherials so dangerous; quickly enough, the body starts to mutate as the aetherial in question figures out how, and starts developing new powers and combat alterations. And the more control they have, and the longer they've been in charge, the worse it gets; regular possessed usually just have a few alterations and rely on the body's previous capacities, while older ones can get new magics and grow to enormous size. And the Aetherial Vanguard, the ones that set the titular apocalypse in motion and have been in control the longest, include titanic monstrosities that were once regular men, up to Theodin "the Flesh Shaper" Marcell, who has practically turned his host into an Eldritch Abomination of meat and aetherial energies.
- Kingdom Hearts:
- When "Ansem"/Xehanort's Heartless takes control of Riku's body in the first game, he transforms it into one resembling his own before he became a Heartless.
- When Master Xehanort possesses Terra in Birth by Sleep (creating the being who later possesses Riku), this act immediately turns Terra's hair white and his eyes gold. As Terra already bore great resemblance to Master Xehanort in his youth, Terra-Xehanort virtually becomes a dead ringer for his original incarnation.
- When Vanitas possesses Ven in the same game, it turns Ven's eyes gold and gives him Vanitas' outfit.
- One of the major reveals of Dream Drop Distance involves the true scope of Xehanort's plans: Organization XIII was originally created so that Xehanort could find candidates to divide his heart among as part of a greater plot to eventually gain access to Kingdom Hearts. This is why Nobodies like Xigbar and Saïx have physical features their original selves didn't possess, such as gold eyes, Pointy Ears, and lighter hair colors — they're slowly turning into Xehanort, and thus taking on his general appearance. As Kingdom Hearts III reveals, the rest of the "real" Organization's members all at least possess gold eyes. Even Xion has them, even though she's hooded throughout her entire time as a vessel.
- Kirby games show this as a possible side effect of being possessed by Dark Matter. For instance, King Dedede grows a Belly Mouth, and a friendly Waddle Dee becomes a Waddle Doo. This is always undone once they're freed from its control.
- Legacy of Kain: Raziel learns to occupy corpses and shape them into an image of himself.
- When an Ing from Metroid Prime 2: Echoes fuses itself to a host, the host takes on a darker, mutated appearance as a direct result, with Spikes of Villainy and a single, huge compound eye taking up most of their face.
- One of the Odio manifestations in Live A Live is a rather unusual case of this. O. Dio in the Wild West chapter is the result of the ghosts of the Seventh Cavalry possessing and transforming a victim. In his natural state, O. Dio is a horse. (This is because the Seventh Cavalry is possessing the Sole Survivor of the battle, which just happened to be a horse in real life as well.)
- Persona 5:
- Humans who have had their Mental World messed with by The Conspiracy end up with Blank White Eyes and start bleeding sludge-like black blood from their mouth and eyes.
- When first offered a contract by their "other self", characters gain Supernatural Gold Eyes just like the beings native to the Cognitive World.
- Pokémon Legends: Arceus has Basculegion, a Water/Ghost-type evolution of White-Stripe Basculin that occurs when one Basculin gets possessed by the souls of other Basculin that died trying to swim upstream. It also counts as a Mind Hive since the souls still act with wills of their own.
- In Shin Megami Tensei IV, reading certain kinds of books will transform the reader into demons; this trope is implied in the process. It's most clearly seen in the case of Ogun and Dantalion, though Issachar and the victims of Red ingestion might also count.
- Soul Series: Those who would wield the cursed blade Soul Edge become enslaved by its desire to feed on souls. Part of this process typically involves growing a hideous claw on one of their arms. The only exceptions to this seen are Algol (whose Heroic Willpower allowed him to completely override Soul Edge's evil influence), his son Arcturus (presumably because he was killed by Algol in self-defense not too long after stealing Soul Edge and attacking his father), and Cervantes (who suffered no physical deformities when he was using it, though the non-canon interquel Soulcalibur Legends retroactively gives him the mutated arm to line up with all the other Soul Edge wielders). Interestingly, Soulcalibur V shows that game's Nightmare (Soul Edge using Raphael's body as a host) being able to voluntarily suppress the deformities and take on a regular appearance in order to blend in as Graf Dumas.
- In the 2010 remake of Splatterhouse, the Terror Mask transforms Rick, a somewhat scrawny college student, into a hulking overly muscled top heavy behemoth with glowing yellow eyes. The Terror Mask can mutate Rick even more by making bone spikes erupt out of his body as a Super Mode, though it dials it back when it realizes that Rick's body cannot handle the strain for long.
- Super Robot Wars UX: Noval Dilan becomes the physical embodiment of Kali Yuga (with Durga's appearance) and grows to the size of a planet.
- Tales of Destiny: Hugo's body takes on Miktran's appearance in the remake when he became strong enough to possess him completely, though it's implied he used the Eye of Atamoni to do it and it wasn't a necessary part of the takeover.
- Tekken 5 reveals that Jinpachi Mishima, the founder of the Mishima Zaibatsu and Heihachi's father, was imprisoned under the family estate and dojo Hon-Maru 40 years before the events of the game by Heihachi. After he died, a demonic entity took control of his body, bringing him back to life once more, and Jinpachi has no control over it. The demon also completely twists Jinpachi's physical form to go One-Winged Angel: spikes grow from his elbows, on his back, and on his legs; he acquires a second mouth that replaces his stomach; his skin turns purple and gains muscle structure; and his eyes turn yellow with a red aura around him.
