When Alien: Earth makes its long-awaited debut tonight on Hulu and FX, it will introduce fans of the Alien franchise to a vast cast of new characters. As you’ll learn as soon as Alien: Earth starts, some of these new characters are going to be ordinary old humans, just like us. Some of these are going to be classic Alien androids known as synthetics. You know, the ones who can imitate human behavior, but bleed milk? Still others will be considered cyborgs, people with nifty augmentations that make them more powerful. Most important to Alien: Earth of all, though, is a new race called hybrids.

Alien: Earth‘s heroine Wendy (Sydney Chandler) is the first hybrid ever made. We first meet her on “Neverland,” the private base of child prodigy Boy Kavalier (Samuel Blenkin), as Marcy, a little girl with terminal cancer. Boy Kavalier and his team have cracked the code on how to upload human minds into synthetic bodies, only they can only make the science work with the more elastic brains of children. Over the course of Alien: Earth Episode 1, we watch as Boy Kavalier assembles his own tribe of “lost boys” all led by Wendy.

When Weyland-Yutani deep space research vessel crashes on Boy Kavalier’s land, Wendy encourages the kids to embark on an adventure to save her brother Hermit (Alex Lawther) from the disaster area. Boy Kavalier, on the other hand, is more interested in the five alien species that were on board his rival corporation’s ship.

So who exactly are all these new characters? Who’s a human, who’s a hybrid, and who is something else? Where have you seen the cast of Alien: Earth before?

Here’s everything you need to know about the cast of Alien: Earth…