Summary

• Many Star Trek aliens look humanoid due to the practical and budgetary limits of producing TV series.
• Not all aliens resemble humans in Star Trek, such as silicon-based creatures like the Horta and mysterious interdimensional beings like the Kerkhovians.
• Star Trek explores a wide range of intriguing and unique alien species, from incorporeal beings like the Organians to gas giant inhabitants like Species 10-C.

Many of Star Trek's most well-known aliens look basically human, but sometimes Starfleet encounters truly alien creatures who do not resemble humanity at all. Star Trek: The Next Generation season 6, episode 20, "The Chase" provided an in-universe explanation for why so many Star Trek aliens look like humans with bumpy foreheads. Billions of years ago, a humanoid species now referred to as the Progenitors seeded planets across the galaxy with DNA that would evolve into lifeforms similar to themselves. Star Trek: Discovery season 5 has provided more insight into these mysterious ancient humanoids and their technology.

The practical reason that so many Star Trek aliens are humanoid is, of course, that all actors are human, and, as a television series, there were practical and budgetary limits to how Star Trek could create aliens. More than a few energy-based beings popped up on Star Trek: The Original Series, but they often possessed humanoid hosts or shifted into a human shape so that actors could portray them. Even the Q and the Changelings, who could take nearly any form, take humanoid forms when interacting with humans. In modern Star Trek, humanoid aliens remain the norm, even as make-up and special effects technology has advanced. But it's always fascinating to see Star Trek aliens who bear little to no resemblance to humanity.

10 The Horta

Star Trek: The Original Series Season 1, Episode 25 - "The Devil in the Dark"

In one of Star Trek: The Original Series' most iconic episodes, Captain James T. Kirk (William Shatner) and the crew of the USS Enterprise travel to a mining facility to investigate a series of deaths. Once there, they find a strange subterranean creature that is a silicon-based lifeform. When Spock (Leonard Nimoy) mind-melds with it, he discovers that the creature is called the Horta and only killed the miners to protect its eggs.

"The Devil in the Dark" contains the first use of the phrase, "I'm a doctor, not a...," when Dr. Leonard McCoy (DeForest Kelley) says, "I'm a doctor, not a bricklayer!"

At the end of Star Trek's "The Devil in the Dark," the miners agree to leave the Horta and its eggs alone, and after the new Horta hatch, they help create tunnels within the mine. While the Horta may look like nothing more than a moving molten rock, it remains one of Star Trek's most unique aliens. With its classic Star Trek premise, "The Devil in the Dark" remains one of the franchise's most memorable episodes.

9 The Kerkhovians

Star Trek: Strange New Worlds Season 2, Episode 5 - "Charades"

When Nurse Christine Chapel (Jess Bush) and Lt. Spock (Ethan Peck) do a flyby of the Kerkhovian moon in Star Trek: Strange New Worlds, their shuttlecraft gets pulled into a dangerous vortex. While Chapel is unhurt, Spock has been turned completely human. Captain Christopher Pike (Anson Mount) then contacts the Kerkhovians who "repaired" Spock, but they say that since "remediation" was made, no further contact will be necessary.

The Kerkhovians once built a civilization on the moon of the planet Kerkhov but later moved to interdimensional space. As powerful non-corporeal beings, the Kerkhovians were able to repair the shuttle and heal Spock, but they were confused by Spock's combination of Vulcan and human DNA. Chapel eventually flew a shuttle into interdimensional space and convinced the Kerkhovians to return Spock to his proper half-Vulcan/half-human state.

8 The Tholians

Star Trek: The Original Series Season 3, Episode 9 - "The Tholian Web" & Star Trek: Enterprise