Mass Effect introduced fans to races beyond their wildest dreams. As this space opera progresses, the relationships between species become more nuanced, new races are discovered, and Shepard must try to make friends with all of them. That is, they had better, if they want to have a chance of halting the oncoming Reaper invasion.
The galactic community has been evolving since long before humans joined it, and each species has an array of special interests, relationships with the other species, and outlooks on the interplanetary system. To help you keep track of the array of races that fans encounter in the Mass Effect series, this handy list tracks every one and where they're from in the galaxy.
20 Salarians
The Salarians are a race of amphibious humanoids known for their intelligence. They think in non-linear patterns and have extraordinarily fast metabolisms that cause them to think, talk, move, and work faster than other races.
Salarians have noted that, to them, other races seem slow and almost infuriating, like a video played at half speed. Though they've expanded across the galaxy by Shepard's time, their homeworld is the planet Sur'Kesh from the Pranas System of the Annos Basin – a wet, lush, and dangerous jungle world.
19 Volus
The Volus are a short and stout people. When seen off their home planet of Irune, they wear pressure suits and breathers. That's because of Irune's particularly high-pressure atmosphere and the Volus' subsequently ammonia-based biochemistry.
The species is a "client race" of the Turians, essentially meaning they're under the latter's protection. Though Volus can't compete physically or mentally with the other races, they are known to be shrewd businesspeople. Their economic network is essential to the galactic community.
18 Keepers
Keepers are a species only ever seen on the Citadel. When the space station was created by the Reapers, they also genetically engineered the Keepers to be its maintenance crew. Between the Reaper's cycles, the Keepers ensure that the Citadel continues functioning so that the next batch of species will be able to locate and use it.
Among the galactic population, Keepers are controversial – some think they need to be paid for their labor (despite the fact that they don't earn any money) while others feel they should be left alone to do what they're passionate about.
17 Batarians
Batarians have a bad reputation in the galaxy. They're generally thought to be pirates, slave traders, and smugglers. This is true for a large number of Batarians, who thrive in the chaotic Terminus Systems – but not for all of them.
The Batarian homeworld is Khar'shan, which falls within space that humanity is actively colonizing. As a result, Batarian-Human relations are hostile (at best). Since Khar'shan doesn't fall under Citadel jurisdiction, there's no way to verify their population numbers, their military fleets, or their economics – unless you believe the Batarian propaganda.
16 Collectors
Collectors were once Protheans. However, when the Protheans were faced with the Reaper threat in their time, a large number became indoctrinated. These Protheans pushed politically to find an alternative to killing the Reapers and managed to stall enough that the Reapers were able to wipe out the species. Afterward, what remained of the indoctrinated Protheans became the Collectors.
Since then, they have mostly stayed out of the way of other space-faring civilizations, only appearing occasionally to make shady bargains for sentient beings' lives. The Collectors were introduced to fans during Mass Effect 2; that game features them heavily as the main antagonists and ultimately asks the player whether they want to destroy or preserve their immense knowledge and technology.
15 Turians
Turians raise their children to become loyal, disciplined adults. They might be considered rigid by the standards of other races, but their fleet is the largest of the Council-allied races. When Humans first met alien species and the Council, there was a huge war in which the Turians played a large part.
As a result, Humans and Turians are known to be hostile with one another. The Turians' home planet is Palaven, which is found in the Trebia System of the Apien Crest Cluster. Palaven was never occupied by an invading force until the Reapers arrived.
14 Geth
The Geth are one of the only races in the galaxy with no organics – they are AI who live in robotic bodies. The Quarians created the Geth to help them with work and so that Quarians didn't have to die in wars. However, the Geth eventually gained sentience and began to ask their masters reflective questions about why they existed.
The Quarians attacked, fearing what they have wrought, which resulted in a war between the species. Quarians were driven off their home planet and their colonies into space. The Geth still remain on the homeworld, Rannoch, and in the Perseus Veil (a region on the edge of the Terminus Systems where the Geth live).
13 Krogan
Krogans mostly live on their homeworld, Tuchanka. It's a harsh, chaotic planet with plenty of vicious creatures the Krogan must contend with. Ruins of their once-great civilization are now husks of their former selves.
When their ability to reproduce was severely limited by the biological weapon the Genophage, Krogans retreated to focus on nurturing their people. Female Krogan usually remain on Tuchanka so that they can attempt to successfully reproduce. Male Krogan may stay on Tuchanka but also often leave to become mercenaries in the galaxy.
12 Raloi
The Raloi, depicted here by TacoWrath on DeviantArt, are a species that are never seen in a Mass Effect game, nor do they appear in any of the books or comics. They were introduced by the Twitter account run by BioWare, Cerberus Daily News (now inactive).
Raloi are feathered creatures who made contact with the Elcor and Asari first, then the rest of the galaxy. Their homeworld is a planet named Turvess but they aren't actively involved in the galactic community. In fact, when the Reapers invaded, the Raloi actually retreated back to Turvess in the hopes that the Reapers would think they weren't advanced enough to destroy.
11 Reapers
Reapers are a partially synthetic, partially organic race. Each individual is a starship, capable of taking off from planets, traveling through space, and attacking. Their design was based on a now-extinct species called the Leviathans, whom the Reapers destroyed at the order of the Catalyst.
Every 50,000 years since their creation, the Reapers attack space-faring life and wipe it out, allowing another species to flourish. Between these "cycles," Reapers linger, dormant, in dark space (the mostly empty regions between galaxies) before attacking again (unless you don't want them to, which a mod can make happen).
10 Virtual Aliens
Virtual Aliens, depicted here by u/Flint13345 on Reddit, are a race that came into contact with the Citadel Council during 2185 (around the time of Mass Effect 2). They're simply called "Virtual Aliens" because we're not sure what they call themselves and the race exists entirely in a virtual reality aboard a spaceship that wanders the galaxy.
When they came into contact with the Council (the Salarians, first, then the rest) it was because they were running out of fuel. The Virtual Aliens agreed to share their technology in exchange for assistance and supplies.
9 Vorcha
Vorcha are a race that communicates non-verbally, often by using aggression. As a result, they have fallen in with less than reputable galactic groups; they are often recruited into mercenary groups. Vorcha have unique bodies that actually evolve as they live and face challenges.
These evolutions are passed down to their children. As a result, the species no longer involves as a collective like other races. Their home planet, Heshtok, has been likened to hell by human military members – it's dangerously volcanic.
8 Yahg
The Yahg are a species that hasn't yet achieved their own advanced space travel. They were encountered by the Citadel Council and they attempted to make first contact with the Yahg, but the entire Council delegation was slaughtered upon arrival.
As a result, the Council declared that Yahg were unsuited to be a part of the galactic community (at least for now) and instructed Council-allied races to keep their distance from the Yahg homeworld, Parnack.
7 Rachni
Rachni are a species of sentient beings who existed during the time of the Protheans. They were thought to be extinct following the Rachni Wars – in which the Council races fought against the Rachni – until living members of the species were discovered by Commander Shepard on Noveria.
Their homeworld was once the planet Suen in the Maskim Xul System of the Ninmah Cluster, but Shepard gets to decide their fate during Mass Effect 1: the Queen begs the player to free her and allow her to teach her children forgiveness. Shepard can agree or choose to destroy her.
6 Quarians
Quarians are a race with no home planet. They live on a collection of space ships called The Migrant Fleet ever since being kicked off their homeworld and colonies by the Geth.
As a result of needing to constantly maintain out-of-date or damaged space vessels, the Quarians became known for their expert technological prowess. Whether the Quarians ever return to their homeworld is a choice that the player must make during the course of Mass Effect 3.
5 Asari
Asari are perhaps the most respected race in the Milky Way. They are a race of exclusively female-presenting beings with cool skin tones like blue and purple. Their diplomatic ties, biotic abilities, and general grace have made them one of the Council's most influential species.
The Asari homeworld is a planet named Thessia, located in the Parnitha System of the Athena Nebula. It can only be described as a paradise, with reportedly stunning architecture, unbelievably low levels of crime, disease, or hunger, and a superior economy.
4 Protheans
Protheans are the only extinct race to appear on this list because one single member of the species managed to survive – Javik, a companion of Commander Shepard. The Protheans lived in the Reaper cycle immediately preceding the one which players live through in the Mass Effect trilogy.
Their technology, when discovered by younger races, allowed for incredible leaps in science and technology. Many space-faring races got their start by studying Prothean artifacts, including the one which humans discovered on Mars. The name and location of their homeworld, however, has been lost to time.
3 Drell and Hanar
What is left of the Drell race is only alive thanks to the Hanar. When the Drell home planet, Rakhana, began to experience devastating climate change due to industrial expansion, the Hanar emigrated as many as they could to the Hanar homeworld of Kahje.
Now, both species live in peace on Kahje, though some changes have been made to accommodate the Drell. Kahje's surface is 90% water, and the Hanar people are akin to giant jellyfish – they use force fields to leave their oceans. Drell needed something a bit different (and less humid).
2 Elcor
The Elcor are large and slow-moving due to the high gravity on their homeworld, Dekuuna. Indeed, the Elcor take everything slowly, from their economics to their military endeavors. They wouldn't mesh well with the Salarians.
Elcor are blessed that Dekuuna is covered in natural resources, and they know it. The forests, precious metals, and more are protected by law. Dekuuna is covered in grasslands around the equator, which is where most of the Elcor live anyway. They make migrations to different regions for the wet and dry seasons despite technological advancements, out of a respect for tradition.
1 Humans
Humanity has come a long way in the 100+ years between the modern-day and the time of the Mass Effect games. Earth became humanity's base of operations as they rather ruthlessly spread out into the galaxy. This colonizing approach has made humans both friends and enemies in the interplanetary community.
When humanity found a Prothean data cache on Mars, they were finally able to reach the levels of technological advancement seen in other Council races. Since then, humans have been the newcomer to the galactic table.