The Zerg are arguably the most memorable part of the Starcraft series, to the point where they might as well be the mascot. It's easy to see why since the Terrans are just humans, and that's boring, and the Protoss are also fairly generic just being the super-advanced aliens with psychic powers.
In comparison, the Zerg swarm is terrifying, just an all-encompassing mass of, well, bio-mass intent on eating the entire universe, and it's nearly impossible to stop them. That being said there are a few things that you need to know about the Swarm.
10 Based Off The Tyranids
This might come as a surprise to many people, but the Zerg are actually based loosely on the Tyranids from the Warhammer 40k universe. There are similarities, like the never-ending need to consume and the hive mind that both species tend to have. This similarity isn't due to just mere inspiration but rather because the original Starcraft was originally going to be a 40K title until Games Workshop pulled out. This lead to the developers building on what was already there to make the game we have now.
9 Zerg Rush Easter Egg
The Zerg Rush is one of the first and most common tactics that was seen in the early Starcraft multiplayer. Basically, due to the Zerg specializing in building a lot of generally weaker units quickly, players were able to build up a large number of Zerglings very fast at the start of a multiplayer match and attack an enemy base early on.
This tactic was so popular it became a meme and google decided to make it an Easter egg in their browser.
8 They Were Originally Going To Be Space Vampires
After the deal with Games Workshop fell through, the developers at Blizzard had to rework the assets and change the idea of the game around. As we know, ultimately they decided to g with something that when you think about it is fairly close to the Warhammer 40k universe, albeit a lot less grim dark and a lot more hopeful. One of the early plans after the split was to have the game be based around space vampires, with those vampires likely having some influence on the Zerg.
7 Kerrigan Was Named After A Rival
The woman that would go on to become the queen of blades, Sarah Kerrigan, has a name with a few different influences and meanings. When she was first introduced, fans figured that she was named after Olympic figure skater Nancy Kerrigan, who famously had her leg broken by goons hired by the husband of one of her competitors Tonya Harding.
Her character was actually based on one of the series' early rivals Command & Conquer and their character of Tanya.
6 The Creep Is Alive
The Creep is a unique mechanic and part of playing as the Zerg faction in the Starcraft franchise. The Creep, similar to The Blight in Warcraft III for the Undead, marks the areas where the Zerg can build their structures. The Creep expands with every Zerg structure that is made. Considering how the Zerg are based around being the perfect biological beings in the lore, it makes sense that the Creep is not only a living organism, but also sentient in some capacity.
5 Zerg In Space!
Of course, there are Zerg out there in space, they are literally aliens, but when we say Zerg in space we mean that very literally, as in outside of any planet's atmosphere. The Zerg have to travel to the planets that they want to infest somehow, and they aren't really known for having big space ships. While they do have things that work in those ways Zerg are also able to fly through space (with wings somehow) and survive the vacuum of space.
4 Originally Herbivores
We learn in Starcraft II: Heart of the Swarm that the Zerg not always as we see them now. we actually travel to a planet where the Zerg are closer to what they originally were as Primal Zerg. Despite Primal Zerg being ancient, there was a form of Zerg even before them. The Zerg are based around adaptation and evolution but all that had to start somewhere. Originally many different types of Zerg were herbivores including Brood lords, hydralisks, ultralisks.
3 Corruptors' Movement Is Impossible
As we've already been over, the Zerg (and Terrans and Protoss as well to be fair) tend to look at the laws of physics and either laugh at them or just eat them. The Zerg are able to go into space outside of any transports they have and would only die due to lack of sustenance. Another impossible feat that the Zerg achieves like it's nothing is the movement of the Zerg Corruptors, which without any wind, should be impossible.
2 One Egg To Fit Them All
As most Starcraft players, especially Zerg players, know, the Zerg spawn their units in a different way to the Terrans and Protoss. Instead of having different buildings that spawn different units, the Zerg are hatched from eggs from the main Zerg building. The way this is shown in-game is that whichever Zerg unit that you want to spawn comes from an egg made by a Zerg larvae. In the lore this is canon, meaning that even the massive Ultralisk has the exact same egg as the Zerglings.
1 Overlords Are Really In Charge
If "You must construct additional pylons" wasn't such a meme-able phrase then the Zerg equivalent "Spawn more Overlords" might have taken its place, especially the version that we get in Starcraft it where it is just so much more meaning but sounds hilarious when given the phrase. In the lore, Overlords control the hive mind on the field meaning that in the case of the lore, that more Overlords are needed to control the swarm, and if Overlords are killed, the Zerg should go out of control.