While Prometheus hinted at the origins of the Xenomorph, Alien: Covenant explains exactly where the fearsome extraterrestrial creature came from.

Warning: SPOILERS ahead for Alien: Covenant

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Alien: Covenant is now in theaters, and while it doesn't completely bridge the gap between Prometheus and Alien, it does answer one major question: where the franchise's titular alien came from. Over the course of the movie, it's revealed that the android David (Michael Fassbender) is the creator of the xenomorph, using gruesome biological experiments to create what he sees as the perfect organism.

When the xenomorph first burst onto our screens in Alien, in 1979, its origins were shrouded in mystery. We knew what it looked like - a ferocious-looking creature, black-skinned, with a sharp, muscular tail, a curved, oblong head, acidic blood that would melt your face off and a powerful inner jaw to knock your brain out too. However, like Ellen Ripley (Sigourney Weaver) and the rest of the Nostromo crew, we didn’t know where it came from or what it wanted - other than to kill every human it came into contact with - and it wasn’t until James Cameron's Aliens that it was given an actual name. Lieutenant Gorman (William Hope) was the first one to call it the xenomorph, by putting together the Greek words for alien (xeno) and form (morph).

With every new instalment in the Alien franchise, new theories were put forward as to the xenomorph’s back-story, because its creators - Don O’Bannon, Ronald Shushet and Ridley Scott - had held back from actually giving it an official one. Before the arrival of Prometheus, some people had speculated that the parasitic aliens were the alpha predator of their own harsh ecosystem on the planet Xenamorph Prime. After Prometheus, theories focused more on the Engineers being the creators of the savage species.

Now with the arrival of Alien: Covenant, Scott has decided it is time the world knew the truth about his fearsome extra-terrestrial monster, but in order to properly explain the Xenomorph’s origin story, we first need to remind ourselves of some key plot points in Prometheus. At the end of the 2012 movie, Elizabeth Shaw (Noomi Rapace) escapes on the Engineer’s ship with a decapitated (but still functioning) David (Michael Fassbender) on board and hundreds of cylinders of black liquid - which contain a virulent biological weapon.

We first saw the effects of that liquid on humans when David tainted Charlie Holloway’s (Logan Marshall-Green) drink with it, and when Fifield (Sean Harris) fell face-first into a puddle of it. Holloway was killed before he mutated into the monstrous being Fifield became, which, though deadly, was nothing compared to the xenomorph. Shaw herself “births” her own alien offspring, the trilobite, after having the liquid accidentally sexually transmitted to her by Holloway. She cuts it out of her stomach before it can claw its way out of her, and it ends up latching onto the Engineer, causing a different strand of the alien species, the Deacon (AKA proto-xenomorph) to burst out of its chest. This alien shares a lot of characteristics with the xenomorph but, as we discover in Alien: Covenant, David is to thank for the real thing.

In the new prequel we learn that Shaw and a mended David did arrive on the Engineers’ planet. Shaw had wanted to find out why the Engineers decided to destroy humans, whom the Engineers themselves created, but instead David decides to let the dangerous substance loose on them, subsequently wiping their entire population out. David turns the Engineers’ stronghold into his own personal lab, using the black liquid in experiments to create the first iterations of the alien species. It turns out the alien’s parasitic nature is inherited from the native wasps David had been experimenting on - which lay eggs inside their prey and, upon hatching, the larva eats the prey from the inside out.

Sound familiar?

After exhausting the planet’s creatures and organisms in his experimentations with the black liquid, David ends up “sacrificing” Shaw to his genetic engineering. In a way she was the first queen, as it was through her female reproductive system that he was able to create the eggs containing the facehuggers. However, with no more humans to experiment on, David couldn’t progress any further.

Enter the Covenant crew who descend on the planet after picking up on a transmission of Shaw singing an old John Denver song - a honey pot trap set up by David in order to ensnare any passing human ships. Before they meet David, a couple of crew members are infected by embryotic spores. This leads to a more natural kind of xenomorph - called a neomorph and white in colour – to burst out of one crew member's back and another's throat. In comes David to save the remainder of the crew, but obviously not out of the kindness of his synthetic heart. Fresh humans provide just what he needs to take his scientific exploration to the next level and sadly for Captain Oram (Billy Crudup) he becomes David’s new guinea pig.

Oram gets tricked into taking a hugger straight to the face  - from the batch of eggs evolved using Shaw - and out of his chest comes David’s “perfect organism” - the first horrifying xenomorph. This creature is the final result of David’s Machiavellian creation cycle - the outcome of his ruthless pursuit to create an alien species far greater than the human that created himself.