Over the course of time, advances in special effects technology and make-up techniques can allow a series to have bigger and better creatures and monsters. Often, the original version of a creature might not have been that cool or interesting, and so a new model was established using the more advanced technology. In other cases, technological advances can't be credited for the retcon: sometimes a creature's look will change as a series progresses due to Art Evolution
This is often seen in fantasy or Sci-fi media.
- In Doctor Who, the original Daleks were clunky and, because they were mounted on tricycles, had difficulty with rough terrain. And stairs? Forget about it. CGI allows the new series to feature flying Daleks who are capable of traversing stairs and interstellar space without trouble. Heck of an upgrade there.
- The Cybermen also became much more menacing looking and ominous.
- Another Doctor Who example: the Macra. Old series Macra look like this◊. New series Macra look like this◊.
- The Silurians in the old series were done with rather clunky (and practically immobile) masks. The new ones are still created with makeup, but it's far more sophisticated and lifelike. However, the old ones were more alien, featuring sucker-like mouths and three eyes. The new ones look more like green, scaly humans. This is acknowledged in-show as being different subspecies.
- In Buffy the Vampire Slayer, Oz's wolf form went from an animatronic to a much sleeker full-body skunk-wolf suit.
- The Klingons in the original Star Trek series were basically swarthy Human Aliens, but advances in make-up technology allowed them to become one of the best (and most believable) examples of Rubber-Forehead Aliens. This example is notable in that Gene Roddenberry always claimed that the "new" Klingons were how they would have looked back in the 1960s if it had been possible at the time - he considered the new Klingon look to be how the old ones always did but there just wasn't the budget to show it. (The original Trek often didn't have the budget even when it had the means. Why'd the old-school Romulans wear helmets? Easier than making custom pointy ears for everyone - which is also why several Vulcans wore the same helmets in "Amok Time"!) In-universe, the difference didn't exist until attention was called to it in an episode where the Star Trek: Deep Space Nine crew went to the past. Then Star Trek: Enterprise comes along, with pre-TOS Klingons looking like the "new" ones! Yes, we do at long last get an explanation. None for Romulans (see below) though.
- It's worth pointing out that Worf's make-up alone improved significantly after the first season or two.
- Both the Worf and Data makeups not only got better looking as the series progressed, they also became substantially quicker. Everyone was happier with the later makeup call for the two characters.
- Trek's Borg also received an upgrade in Star Trek: First Contact, losing the chalk-white skin in favor of glistening, apparently decaying flesh. They were given more implants on their bodies, and their ships were redesigned.
- They also got a major design change between their first and second appearances. The second features a much more modular design to how the prosthetics were done, allowing more drones to be made up than the individual custom jobs used in the first appearance. The chalk-white skin was largely to save on labor in makeup, and techniques using quick airbrushing allowed the hard bits (like deeply shadowed eyes) to be done fast by a small number of highly trained makeup people after more generally trained ones did the bulk of it, again so that more drones could be made up.
- Romulans had the same make-up as Vulcans in TOS and some early TNG. In later seasons of TNG and all following series, they have a distinctive V-shaped ridge on their foreheads. However it seems that this retcon did not apply to all: there are later examples of Vulcans and Romulans passing as each other, suggesting there are minorities among both who look like the other.
- In the new movie - which isn't a Reboot ( villains from the Trek Verse as we know it changed history. It's not out of continuity any more than the last two seasons of Eureka.) all the Romulans we see are smooth-headed.
- The Covenant from the Halo series have become more life-like and more scary-looking as computer animation technology has improved. Elites became stouter with more practical looking armor, Grunts more reptilian and red-eyed, and Brutes from hairy unarmored giants to weaker, armored, and shaven fellows. Their designs most deviated in Halo: Reach, where the Elites' armor became very ornate and alien while the Brutes turned more ape-like, though still shaven.
- Dragon Age II's qunari now sport horns in order to differentiate them from the other races. The official explanation as to why the qunari seen in Origins don't have horns is that the qunari who are naturally born hornless, such as Sten and the members of his squad, are considered special and are given special tasks, such as scouting foreign lands, while the other qunari seen in Origins are Tal-Vashoth mercenaries who typically remove their horns when they leave the qunari.
- The hurlocks have also changed, appearing a few shades lighter, smoother-skinned, and with blunter teeth in the sequel.
- In the first Metroid, due to graphical limitations, Kraid and Ridley are both the same size as Samus. By the time Super Metroid came around, Kraid was two rooms high, and Ridley was at least three times the size of Samus. Zero Mission retcons the Super design into canon.
- Super Metroid also adds a "fake Kraid" that's slightly taller than Samus and much easier to kill outside of the real Kraid's room: this is both a reference to the size difference in the earlier games as well as the fact that the NES game had multiple Kraids, but only one of them was the real one.
- Deus Ex: Human Revolution, more than 10 years since the original Deus Ex, has mechanical augmentations that are significantly more advanced and useful than the un-lifelike ones in Deus Ex. The excuse is that this is right before a great collapse which occurs prior to the beginning of Deus Ex and before the rise of nano augmentations.
- Practically every memorable demon in the Doom series was completely redesigned for Doom3. Most of these redesigns made the demons appear much scarier and more formidable opponents for the player. The original imp, for example, was a large, brown creature with spikes on its shoulders that would slowly advance towards the player while hurling fireballs at them. The new imp is a slimmer grey creature with no spikes and ten eyes on its head that is capable of climbing walls and has incredible jumping ability that allows it to clear the distance across an entire room in a single leap and generally attacks with a much more aggressive style.
- The Elder Scrolls series has surprisingly averted this for the most part, despite major overhauls to the graphics with each new game release. Most of the races and creatures that appear in each game have kept the same look, with only improvements in the quality of their appearance, not to the appearance itself. One area where it has been played entirely straight has been with the Argonian race. Arena displayed them as gray skinned humanoids. Two games later, Morrowind◊ turned them into bird-legged, iguana-looking people. Oblivion◊ returned them to more traditionally bipedal dinosaur-looking people. Finally, Skyrim◊ has them looking like full blown humanoid Velociraptors. This evolution is possibly justified in-universe as the Argonians worship the "Hist," a race of sentient trees in their homeland of Argonia. Hatchling Argonians drink the sap from the Hist that changes them physically. After the events of the Oblivion Crisis, it is believed that the Hist have been strengthening the Argonians, turning them into more formidable warriors over time.
- This possible justification is backed up by the fact that the Khajiit, who otherwise had the same development as the Argonians (with cats instead of lizards) actually did get a more-or-less official explanation involving physical differences between breeds.