Like copy editors and train conductors, visual-effects designers know they’ve done their jobs if audiences take their work for granted. It’s hard to create, say, a killer robot that looks so real a viewer feels like she could touch it—and “any kind of organic creature or character is exponentially more difficult, because it’s really tough to trick the human eye,” said Alex Kurtzman, executive producer of CBS All Access’s Star Trek: Discovery. His visual-effects designers were tasked with animating a giant tardigrade, an alien the size of a grizzly bear that crawls on eight legs and uses the universe’s “mycelium network” to travel through space.

The peak-TV era has birthed increasingly ambitious and cinematic projects, with budgets that can allow for stunning visuals—not just on pay channels like HBO but across cable, network television, and streaming. Given this, it’s no wonder that TV’s computer-generated beasts have grown ever more elaborate and believable. (In uncertain times, art also tends to get saturated with monsters, literal and otherwise.)

It took the Discovery crew six months to render their trickiest creature and to ensure that the tardigrade could believably convey emotion—a common test for visual-effects teams. The creation, Kurtzman said, “spoke to one of the core tenets of Star Trek. What seems to be alien and foreign and scary and monstrous is only something that we don’t yet understand.”

Usually, designers focus on the eyes when trying to give a creature a personality. But what happens when your beast doesn’t have any? Discovery’s visual-effects supervisor Jason Zimmerman said that the tardigrade expressed itself mainly via body language and the antennae around its toothy mouth. “You have to use different features on the creature to take the place of what would normally be a human face, because we’re so used to reading human emotions,” he said.

“What seems to be alien and monstrous is only something that we don’t yet understand.”

Netflix’s Stranger Things ran into the same problem with Dart, short for D’Artagnan, Season Two’s tadpole-like “pollywog”—a critter later revealed to be a younger life stage of the villainous Demogorgon. Normally, when animators want to make something appear cute, they enlarge the eyes—but the pollywog is eyeless. So, as visual-effects producer Christina Graff explained, the crew focused instead on making it clumsy, which in turn gave the pollywog an endearing aspect. They also printed a 3-D model of the creature for the actors to hold, which “actually tickled out a lot of performance.”

The pollywog ended up being fairly tactile, but other series presented creatures that were truly out of this world, like the “frog-moth” that showed up on David Lynch’s astounding Twin Peaks: The Return, on Showtime. At the end of Episode Eight, the amphibian-insect lurches out of the ground and crawls into a girl’s mouth. Visual-effects supervisor Pierre Buffin said that the surreal idea came straight from Lynch himself.

“The front has no power, so it’s just moved by the legs, little by little, because it’s not meant to move. It was to make something very strange and weird,” Buffin explained. “If you’re on your belly on the floor and you try to move without your arms, it’s like that.”

Meanwhile, the visual-effects team behind the second season of HBO’s science-fiction puzzle box Westworld toiled to craft mechanical android “hosts” that looked organic. Visual-effects supervisor Jay Worth said they modeled the design labs of Westworld’s park on an Audi factory that co-creator Jonathan Nolan had visited; every section has its own purpose in creating the hosts, as we see in the show’s haunting opening credits. To form different versions of the robots, the designers also had to plan out the history of the park, from the very first hosts to the newest generation.

“We had so many conversations about the organic nature of these bodies,” Worth said. “If you only show a snippet of it, but the work has gone into thinking through all the different pieces, you’re able to fill in the blanks.”