The Klingons have been continually redesigned, but Star Trek hasn't made as many significant changes to its other alien races. The Klingons in Star Trek: The Original Series looked like humans with a vaguely Asian design to them but, a decade later, the Klingons look was changed to an armored, bony-browed, and wild-haired look that began in Star Trek: The Motion Picture into Star Trek: The Next Generation's 24th century era. Star Trek Into Darkness changed the look of the Klingons in the Kelvin Timeline, but it was Star Trek: Discovery altering the Klingons to be hairless and even more alien that drew the most fan ire.

Even though the Klingons have been changed at least twice in the Prime timeline and once in the Kelvin timeline, the same can't be said for the Vulcans, Romulans, Tellarites, Andorians, or even the Borg. Most of Star Trek's other aliens have maintained their signature looks even after minor tweaks. Vulcans always have pointy ears, and the Romulans do as well, although they generally look like more sinister Vulcans, and the Tellarites and blue-skinned Andorians maintain their readily identifiable traits like snouts and antennae, respectively. However, the Klingons seem to lend themselves to change, and each redesign was meant to make the warrior race look more menacing and alien. It's also interesting that the two biggest redesigns, Star Trek: The Motion Picture and Star Trek: Discovery, happened during the 23rd-century era. It indicates that the most popular Klingon look identified with Worf (Michael Dorn) will remain untouched in the 24th and 25th centuries.

Related: Why The Ferengi Never Worked As Star Trek's Klingon Replacements

Star Trek Has Changed Other Aliens (But Not As Much As Klingons)

Trill DS9

Several alien species in Star Trek have been altered from their first appearance, but not to the degree the Klingons have. The Trills are an example of a race that was totally redesigned for Star Trek: Deep Space Nine and they looked very different when they debuted in Star Trek: The Next Generation. Now, Trills are humanoid with spots that run from their foreheads down their bodies, and the original design has been forgotten. Otherwise, the Cardiassians didn't change much; they were merely tweaked to lose their strange headgear and their TNG look was finalized on DS9. As for the Ferengi, their basic appearance didn't change from TNG to DS9, but their personalities did, thanks to Quark (Armin Shimerman) and Deep Space Nine exploring the Ferengi culture more thoroughly.

Yet the Klingons kept on changing, with Star Trek having to retcon explanations that didn't quite stick. In Star Trek: Deep Space Nine season 5's classic "Trials and Tribble-ations," Worf barked "We do not talk about it with outsiders!" when he was asked why the TOS Klingons looked completely different. Star Trek: Enterprise conjured the Augment Virus to justify the changes to the Klingons, but Star Trek: Discovery's revamp of the Klingons never got any kind of explanation. It was merely hinted, as the Klingons grew their hair out in Star Trek: Discovery season 2, that they would eventually look like TNG's Klingons.

When Will Klingons (Besides Worf) Return To Live-Action Star Trek?

Worf appears in a promotional image from Star Trek: Picard season three.

After a 20-year absence, Worf finally returns (as a pacifist) in Star Trek: Picard season 3, and he will look like the same Klingon he always has, albeit older. Worf will be the first major Klingon character to appear in live-action since Star Trek: Discovery season 2, but it begs the question of when the Klingons will return to Star Trek en masse. Star Trek: Strange New Worlds' season 1 finale teased the Klingons, but it's unclear which version - TOS or Discovery's - would show up in Captain Christopher Pike's (Anson Mount) era circa 2259-2260. All of Star Trek's changes, well-meaning or not, made a mess of the Klingons that continues to this day. Hopefully, when the Klingons finally reappear in live-action Star Trek, they won't look different yet again.

Next: Star Trek Is Still Dealing With Discovery's Klingon Damage