Over the course of four games and multiple DLCs to go along with them, the Mass Effect franchise has introduced over 30 video game companions to adventure with Commander Shepard and Pathfinder Ryder. Whether or not any of those companions will make an appearance in the next Mass Effect title remains to be seen, but either way, it's nice to take a trip down memory lane.
To do that, we've broken all of the Mass Effect companions into tiers based on their personal development over the course of the story, their contribution to the plot of their respective games, and their overall effectiveness in battle. The highest is the S tier, which represents the cream of the crop: the most beloved, the most developed, the most effective. At the other end of things is the D tier, which is pretty much lacking in everything the S tier boasts. And in the middle is the B tier--good characters absolutely, but not the absolute best of the bunch.
Within each tier, characters are listed in no particular order. So, without further ado, here's a complete tier list of all the Mass Effect companions.
Mass Effect S Tier
Garrus Vakarian
As stated above, these characters aren't listed in any particular order...except for Garrus. He's the best companion in the Mass Effect franchise partially because of just how present he is throughout the first Mass Effect trilogy. Yes, Garrus is the only companion present throughout the majority of all three games (while the same might be said of Tali, she takes a while to join up in ME2), but he's more than that.
Regardless of whether or not he's romanced, of what personality Shepard has, he's Shepard's best friend. He's always there, always on their side, and always ready to snipe a few baddies in battle. And because of his presence in the games, Garrus's character development is top-notch: he goes from put-upon C-Sec officer bitter at being surrounded by red tape, to turian vigilante, to reaper expert and war hero ready to team up once again with his best pal and the one superior officer he'll always back up. Players get to see him mature over the course of the games, and the final product is a character it's impossible not to love. Therefore, Garrus absolutely deserves the top spot on this tier list.
Mordin Solus
Players' first impressions of Mordin suggest he's a brilliant doctor with a quirky way of speaking, but he's so much more than that. It quickly becomes apparent that his upbeat and fast-paced personality is masking a brain capable of some singularly ruthless calculus, as Mordin was one of the minds behind the genophage that is slowly snuffing out the Krogan race. Mordin's character development and contribution to the story can't be disputed: he goes from anti-hero to hero, sacrificing himself to save the race he once condemned.
Liara T'Soni
Liara is a major player in ME and ME3, and even when she's not a companion in ME2, she's got a massive behind-the-scenes presence. Liara is the one who recovered Shepard's remains on Alchera and made sure those awful moments after the destruction of the first Normandy weren't Shepard's last; for that alone, she deserves a place of honor. Add to that her growth from naive scientist to cunning (yet still friendly) Shadow Broken, and you've got an S-Tier character.
Urdnot Wrex
Yes, Wrex can be killed early on in the series, but that's just not fair to this awesome character. Just as Mordin learns to empathize with Krogan, Wrex is a unique member of the Krogans who learns to communicate and cooperate with other races--including Salarians--even while advocating for his people. And, though he's too busy leading his people on Tuchanka in ME2 to join Shepard, it's understandable. All in all, Wrex is just an all-around great fighter and friend to have.
Tali'Zorah vas Normandy
The evolution of Tali's name says it all. In ME1, she's Tali'Zorah nar Rayya. In ME2, she's Tali'Zorah vas Neema. And by ME3, she's Tali'Zorah vas Normandy, the whip-smart engineer whose story arc throughout the series is truly gut-wrenching and amazing. Her deepening understanding of the Geth race is remarkable, and the final showdown in ME3 (depending on decisions) has the potential to be utterly moving, or utterly heartbreaking. Hopefully, cans can someday see her actual face!
Mass Effect A Tier
Grunt
Grunt is basically Shepard's weird teenage son with wicked shotgun skills. As their relationship develops throughout ME2, Shepard helps Grunt to find himself, so that by ME3, Grunt is all grown up and fighting rachni. Although, as the adorable scenes in the Citadel DLC prove, he'll always look up to Mom/Dad Shepard.
EDI
From helpful Normandy AI to fully-fledged person, EDI's journey throughout ME2 and ME3 is tightly bound to the nature of the overarching plot, while also being fascinating in its own right. Most would argue that EDI was already well on her way to being more than just an AI by the time ME2 ended, but even if she wasn't, gaining a body in ME3 sealed the deal. She's also a great hacker and has a hilariously dry sense of humor for an unshackled AI.
Jaal Ama Darav
Jaal is basically the first "new" alien met in Mass Effect: Andromeda, and he's a tremendous member of his race--even if he rarely feels like it. Not only is he the only native Andromedan on the crew, but he's passionate and unafraid of expressing himself emotionally, something that's really refreshing. Plus, he's a great teammate, even going so far as to give homemade gifts to his fellows on the crew. Poetry and knitted scarves? Jaal's a keeper.
Legion
Legion learning how to be more than just a member of a collective whole is an amazing aspect of ME2 and ME3. The Geth's presence on the Normandy puts it at odds with Tali, but their journey as comrades and key members of their respective races is a huge part of the game.
Jack
Jack is pretty much the personified form of the "edgy character" stereotype, but it works for her. Especially since she doesn't remain only an edgy, angry character from start to finish: she gets her closure and then goes about trying to be something more, even becoming a teacher and, really, caretaker to a group of young biotics. For that, Jack gets kudos.
Thane Krios
Thane boasts an interesting dynamic: he's a deeply spiritual and yet cold-blooded assassin. Thane's desire to make right with his son in the face of impending death in Mass Effect 2 is one for the books, and his ultimate sacrifice in the battle against Kai Leng cements his rightful high ranking in this tier list of Mass Effect characters.
Pelessaria ‘Peebee’ B’Sayle
Peebee, the Asari tech expert, is another of Andromeda's best companions: she's spunky, witty, and has a fun character arc that takes her from free-spirited and unattached to just as free-spirited, but unafraid of forming attachments to the crew that has grown to be her family. She also learns a little more responsibility in terms of making sure her modified tech stays in good hands, which is a plus. Peebee's fun energy is a huge breath of fresh air for the duration of Andromeda.
Jeff 'Joker' Moreau
Joker may not really be a "companion" in Mass Effect. but he still deserves a place on this list, if only because he's the one character who is there for an even longer period than Garrus. Sarcastic and an unparalleled flight lieutenant, Joker maintains his sense of humor despite (or perhaps because of) a condition that effectively cripples him and would do pretty much anything for the Normandy and for Shepard.
Mass Effect B Tier
Vetra Nyx
Vetra is that one friend who can get anything, given a couple days and some calls. She's also one of the first female Turians fans really get to know, which automatically makes her pretty fascinating. Plus, Vetra's development in learning to cool off and not control everything (especially when it comes to her little sister) is definitely a sweet little sub-plot.
Ashley Williams
Ashley Williams and Kaidan Alenko are two sides of the same coin: Shepard's first human companions who go through what we'll call a "rough patch" in Mass Effect 2 and the beginning of ME3. That rough patch is enough to sink Kaidan to an even lower tier, so what's Ashley's saving grace? It's her development from xenophobic soldier to Spectre willing to work and make friends with aliens of all races.
Samara
Samara is an Asari Justicar with some frustratingly black-and-white views on justice, but she's an effective biotic and solid companion. Her subplot in ME3 with her daughters is also something that adds a layer of humanity to an otherwise rather dispassionate personality.
Kasumi Goto
Kasumi is a master thief with a heart of gold--or, at least, silver. Sadly, being a DLC character means that there's really not a lot of content out there for her, and certainly not as much as a full character from the base game. Perhaps she'd be a higher tier if there were, but as it is, B-tier definitely isn't bad for this relentlessly likeable crook.
Liam Kosta
Liam Kosta is a basic "bro" type character. He's fun, and he's got a personality that's easygoing enough for pretty much any type of Ryder to get along with...but that's about it. Still, it's nice to have a character not drowning in angst when the story takes a turn for the more dark and dramatic.
Javik
Conversely, the sole survivor of the Prothean race frequently indulges in some angst over his tragic past--and in fairness, it is pretty tragic. However, Javik also does have a wicked sense of humor that comes out as he gets more comfortable with the crew, and a burgeoning camaraderie with Shepard that's nice to see. Plus, it's nice to put a face to the mysterious Protheans that came before and were killed off long before the events of ME.
Nackmor Drack
Drack honestly feels like BioWare was acknowledging all the love for Wrex and attempting to give players something that wasn't quite Wrex, but similar enough that they'd be happy. And Drack isn't a bad character; he's still in the B-tier. But that's because he feels more like every average Krogan smashed into one, with the exception of being kind of like a gruff grandpa figure to Ryder sometimes.
James Vega
Since Andromeda apparently needed a "bro" character, of course ME3 did too, and that's Jimmy Vega. He even goes and gives Shepard a goofy nickname almost right away, but all in all, he's pretty much just a normal guy. And that's okay, but only okay compared to the rest of the more interesting alien crew.
Cora Harper
Cora is the one who should've gotten the Pathfinder job if Alec Ryder's nepotism hadn't gotten the best of him, but she really only seems a little bit annoyed by it at the beginning of the game. Still, she's got a steadfast dependability about her that's nice to have in the usual collection of outcasts and misfits that usually gathers around BioWare protagonists, and shouldn't be discounted.
Miranda Lawson
Miranda Lawson is actually a pretty darn cool character, even if she comes off as one-dimensional for a good chunk of ME2. Once she gets over that hurdle, there's actually quite a bit going on in her mind, and she's got plenty of other priorities besides those of the Illusive Man. Once her family arc takes place, Miranda thaws out substantially, and her "I quit" message to the Illusive Man (if it happens) is honestly worth bringing her on the final mission for.
Samantha Traynor
Samantha is the pinnacle of the cute, awkward, dorky character-type. Sadly, she's not a full "companion," so she really doesn't have that much screen-time compared to the rest. Still, she and Steve Cortez were the first same-sex-only love interests in Mass Effect history, which makes her stand out.
Steve Cortez
Steve Cortez is that all-around friendly everyman that can fit in with pretty much any social group--as he does with the crew of the Normandy. No, he's not the most interesting of characters by a long shot, but at least he's helpful. After all, he pilots Shepard out of some pretty gnarly situations on the ground.
Mass Effect C Tier
Aria T’Loak
Aria, the self-proclaimed queen of Omega, is only a temporary companion, and normally that'd put her on the 'D' tier. However, Aria has enough of a presence throughout ME2 and ME3, combined with being a ruthless and interesting character, that qualify her for a C-tier position.
Kaidan Alenko
Kaidan Alenko is yet another example of the everyman, agreeable to everyone and easy for female players to romance if they so chose. However, BioWare seemingly didn't count on everyone finding the alien companions way more interesting that the human ones, and Kaidan falls to the wayside in comparison. Plus, his rudeness on Horizon definitely gets a few points docked off from his favor. There will always be Kaidan fans, but in the grand scheme of things, he's just not as effective as some of the other ME companions.
Zaeed Massani
Zaeed Massani is a stereotype like Jack, but his doesn't feel as interesting as hers. Zaeed is that grizzled warrior guy who has done and seen it all, but that's about it. It probably doesn't help that he's a DLC character, and thus just doesn't have the same amount of scripted dialogue as the others.
Nyreen Kandros
As a temporary companion, Nyreen should probably be a tier lower too, but she was just a cool lady. The first Turian female in the trilogy, and she ended up leading a gang of merceneries and sacrificing herself for the good of Omega. For that, she deserves a high place in the list.
Mass Effect D Tier
Richard L. Jenkins
What can we say about poor Richard Jenkins? He was there for about two minutes in the very first Mass Effect, and then he wasn't. Rest in peace, private.
Jacob Taylor
Jacob Taylor has the rough job of being the first companion and only human male companion in ME2. He's probably supposed to be some sort of Kaiden-replacement, and maybe he could be if his personality wasn't as bland as a potato.
Morinth
Morinth occupies the same skillset as her mother, Samara, if she is recruited in Samara's place. However, seeing as she's a serial killer whose relationship track will literally kill Shepard, she gets the bottom tier.
Mass Effect 5 is reportedly in development.