The races within the Mass Effect story each have a unique back story and personal complexity to them. The picture above provides an idea of what some of the races look like but it does not contain all of them, which I plan to makes posts about each race as I continue this blog. The list of races within the galaxy can be portrayed easiest by putting them into two groups: Citadel races; those that actively participate and collaborate with the Citadel's galactic government, and Non-Citadel races, those that don't or did interact with the government but no longer for follow it. Some races also exist out of such lists, but I will have to describe them later as to not spoil too much of the story too quickly.
Citadel Races: Asari, Drell, Elcor, Hanar,
Humans, Keepers, Salarians, Turians, and Volus.
Non-Citadel Races: Batarians, Collectors, Geth, Krogan, Quarians, Vorcha, and Yahg.
If you are interested in knowing more
this website is a good place to go. Also note that this list contains the races that are capable of self-thought, reflective, and sapient overall.