Serving as the middleman between the Commander and the rest of XCOM, Bradford communicates your orders to everyone else and performs all the administrative work, leaving you free to focus on the big picture.
XCOM's Chief Scientist, Dr. Vahlen and her team of scientists are responsible for all research and development carried out under XCOM's auspices. She also oversees the "interrogation" of captured aliens.
Beware the Nice Ones: Officer Bradford mentions that Dr. Vahlen may not look like it, but she is without a doubt the worst nightmare for any captured aliens that get brought back to the base.
For Science!: A downplayed example. She's always eager and interested in what she's researching, no matter how questionable, and will be irate if soldiers use explosives (which destroys valuable research material). She's also the inventor of the alien "interrogation" device and personally oversees each interrogation. That being said, the game still portrays Dr. Vahlen in a good light: She'll thank soldiers for the risks they take in recovering live specimens, will acknowledge that the survival of the soldiers can come first and is disgusted by the aliens' callousness.
Genre Savvy: When Bradford acts as though XCOM has won when you destroy the alien base, she raises an eyebrow and prepares to interrogate/autopsy the Sectoid Commander as well as study the captured Hyperwave Beacon, thinking it was too easy. She's right.
XCOM's Chief Engineer, he and his team of engineers manufacture everything XCOM may require, ranging from Medikits to Satellites. They are also responsible for maintaining and expanding XCOM's HQ and its fleet of aircraft.
The Council of Nations is the financial backer behind the XCOM project. They provide funding and recruits, as well as occasionally requesting XCOM's assistance with special matters.
Bald Of Ambiguity: While the spokesman's face is always hidden in shadow, the light shining from behind him displays enough of his head to show it has no hair atop it... well, on the side we can see, anyway.
Reasonable Authority Figure: Is generally positive and optimistic about you, saying they're sure you'll improve when Council Missions go wrong and are O.K. with less than perfection in monthly reports, only saying that XCOM is clearly not going well if you mess up the month really hard.
Council Mission VIPs
The only person to escape alien captivity, her extraction may allow XCOM to find out what the aliens are doing with their abductees.
Few will survive to see the end of this conflict. Fewer still will possess the skills necessary to end it.
— Council spokesman
Constantly outclassed, outgunned and/or outnumbered, these green recruits are nonetheless XCOM's most valuable resource. With experience, the raw, untapped potential within each one could become exactly what is needed to end the war.
A-Team Firing: It's not unusual, particularly on the higher difficulties, for rookies to miss. A lot. It's especially not unusual to have all four rookies that you brought along to train up unleash their barrage on a single sectoid, only for every single damn round to miss.
Front-line units specializing in offense and mobility, allowing them to close in on the enemy and flank more easily. They can be equipped with either assault rifles for mid-range combat or shotguns for close encounters.
Close Range Combatant: The domain of the Assault, being able to wield Short Range Shotguns or the somewhat farther-ranged assault rifles. Their abilities on the right side are used for offensive bonuses and abilities requiring the Assault to close in, flank, and Critical Hit aliens dead. The left side's defensive bonuses are a bit less strict in their application, but still generally benefit the Assault in trying to see aliens eye-to-eye (and then shooting them).
Critical Hit Class: They're some of the best at inflicting Critical Hits, since they'll be flanking quite often, and shotguns come with above average critical chance rates. The right side of their ability tree is full of bonuses relating to it:
The Corporal "Aggression" passive ability grants 10% critical chance for every enemy the Assault can see, up to 30%.
The Sergeant "Close and Personal" passive ability grants 30% critical chance against adjacent targets, diminishing with increasing distance.
The Captain "Bring 'Em On" passive ability adds up to 1 damage to critical hits for every enemy the squad sees, up to 5.
And lastly, the Colonel "Killer Instinct" passive ability adds 50% critical damage from activating Run & Gun for the rest of the turn.
On the flip side, the Colonel "Resilience" passive ability makes them immune to Critical Hits.
Dodge the Bullet: Their Sergeant "Lightning Reflexes" passive ability lets them dodge one Overwatch shot per turn, allowing them to close with the enemy by going through their field of fire.
Lightning Bruiser: Thanks to the "Run and Gun" ability. In a more subtle example, the Sergeant "Lightning Reflexes" passive ability lets them avoid one reaction shot per turn.
Made of Iron: Has the highest health gain from level ups out of all the classes. Colonel Assaults are likely to be the toughest soldiers in XCOM, especially if certain abilities are chosen.
The Corporal "Tactical Sense" passive ability gives them more Defense for each enemy in sight, up to partial cover-level bonus for 4 enemies.
The Major "Extra Conditioning" passive ability give them extra health, increasing based on the type of armor they're wearing.
The Colonel "Resilience" passive ability makes them immune to critical hits.
Magikarp Power: The Assault's abilities that affect critical chance require consistent investment to be reliable and tend to be overkill against the earlier aliens, which are likely to be One Hit Killed even with the basic shotgun anyway (though said abilities become more crucial on Impossible, as all but the Sectoids require more than one non-critical shot to kill), whilst simultaneously being inadequate for One Hit Killing Mutons and Chryssalids on any difficulty. After the Assault has access to a Scatter Laser and the "Bring 'Em On" passive ability, though, they'll become unmatched at running up to things and obliterating them with one shot. In contrast, the Assault's defense abilities pretty much always come in handy and require no prior investment to be useful.
The Second Wave Absolutely Critical modifier guarantees critical hits against flanked targets, which means less investment is required.
A-Team Firing: Their light machine guns deal damage comparable to sniper rifles, but can still be fired after moving. However, the Heavy's Aim stat is the lowest out of all the classes and their shots will only become reliable at much later levels and a S.C.O.P.E. on-hand.
While their rockets are more accurate, there's always that 10% chance to miss... that is visually shown by the Heavy blatantly aiming off-target.
Crutch Character: The Heavy's 90% accuracy cover-destroying rockets (that are still liable to only go slightly off-course and hit an alien you aimed for if it misses) and ability to fire twice with "Bullet Swarm" or boost Aim by 10 against a single target with "Holo-Targeting" are invaluable when your soldiers are still unreliable shots. The high damage of their LMGs and the utility and area-of-effect of said rockets means they're still useful to any squad much later in the game, but they aren't quite as much of a godsend then.
Mighty Glacier: The Corporal "Bullet Swarm" passive ability encourages staying still to fire two shots on one turn (or fire and reload, fire and move, fire and Overwatch, fire and Hunker Down) and rocket attacks require the Heavy to not move in order to use them. In addition, their durability is above average with the Major "Will to Survive" passive ability reduces damage taken by 2 if in cover and not flanked and the second-highest health growth of any class.
More Dakka: They wield light machine guns, which put out even more rounds if the Sergeant "Suppression" active ability is used. It puts out so much dakka that it has the lowest amounts of shots before requiring reloading out of all the main weapons.
With the Corporal "Bullet Swarm" passive ability, they can fire twice per turn.
The Lieutenant "Rapid Reaction" passive ability lets the Heavy fire a second reaction shot if their first shot on Overwatch hits.
Pinned Down: If the Sergeant "Suppression" active ability is chosen, they can do this to any target of their choice for 1 turn. It does consume twice as much ammo as firing normally, but it reduces the target's Aim by 30 and grants the Heavy a reaction shot should the target move.
The Captain "Danger Zone" passive ability increases its area-of-effect by two tiles.
The Colonel "Mayhem" passive ability adds 1-3 damage to all affected targets based off the Heavy's weapon's tech level.
At the initial Squaddie rank, they get the "Fire Rocket" active ability to use their Rocket Launcher which does... yeah. Does 6 damage to targets hit, fires in a straight line and can be blocked by terrain, has an always 90% to-hit chance, requires the Heavy to not move or fire during the turn to use, and can only be fired once a mission. Can cause Unfriendly Fire. Equipping them with a Blaster Launcher increases damage to 9 and allows it to fire around terrain.
Sergeants can get the "Shredder Rocket" active ability, which does 2 less damage than "Fire Rocket", but increases damage taken by targets hit by 33% for the next 4 turns. Otherwise identical to regular rockets, though a separate rocket supply is used. Equipping a Blaster Launcher upgrades it similarly to regular rockets.
The Lieutenant's "HEAT Ammo" (High-Explosive Anti-Tank) passive ability doubles all damage they deal to robotic enemies (Cyberdisks, Drones and Sectopods), which tend to make even more explosions when they die.
A Captain may choose between "Grenadier" or "Danger Zone" passive abilities, the former granting two grenades instead of one if the Heavy equips a grenade, the latter giving the "Suppression" active ability and all rocket attacks an area-of-effect two tiles greater.
At the Colonel rank, a Heavy can get "Rocketeer" for an extra shot per mission to the "Fire Rocket" ability or "Mayhem" to add 1-3 damage to "Suppression" and all area-of-effect abilities based off their weapon's tech level.
Expert marksmen, they specialize in accurately dealing extreme damage at extreme range with sniper rifles and can also use special shots to hinder enemies.
Boom, Headshot: The first ability they learn, in fact, granting +30% Critical chance and extra damage on a Critical Hit, depending on the tech level of the sniper rifle wielded.
Critical Hit Class: Their sniper rifles have the highest base Critical chance out of all weapons. Further enhanced by some abilities.
The "Headshot" active ability gives their shot an extra +30% Critical chance and extra damage on a Critical Hit if it happens and the Captain "Opportunity" passive ability lets the Sniper Critical Hit on reaction shots.
Do Not Run with a Gun: Without the Corporal "Snap Shot" passive ability, Snipers are incapable of firing their sniper rifles on a turn they've moved, though they can fire their pistol.
Finishing Move: The Captain "Executioner" passive ability aids the Sniper in this, gaining +10 Aim against enemies at 50% or lower health.
Geo Effects: The Sergeant "Damn Good Ground" passive ability lets the Sniper benefit further from this, gaining an extra +10 Aim and Defense for being at a higher elevation level to aliens.
Kill Streak: The Colonel "In The Zone" passive ability sets up a flanking Sniper to do this. Killing enemies that are uncovered or flanked by the Sniper do not take up an action, potentially letting the Sniper fire and kill over and over again.
The farther and thus more improbable a shot is, the more accurate the sniper rifle becomes. Combine with Squadsight for some really long-distance shots.
"Disabling Shot" lets the Sniper target an enemy's weapon, forcing them to reload before they fire again.
Magikarp Power: The Sniper starts out unable to fire their sniper rifles after moving and a "Headshot" ability that tends to not reliably grant critical hits against targets in cover, while the extra damage granted is usually overkill against early-game enemies. Colonel Snipers have the highest Aim in the game and will either outflank aliens and score a Kill Streak of One Hit Kills with the "Snap Shot" and "In The Zone" passive abilities, or kill enemies from across the map with "Squadsight", which allows the Sniper to shoot at enemies any of the squad sees, barring any obstacles blocking the shot (with Archangel Armor to fly up to the highest vantage point possible, they can do so without ever moving from their starting location!). Both will slaughter aliens with contemptuous ease and be difficult to hit wherever they take cover due to the Major "Low Profile" passive ability making any cover they use count as full.
Long Range Fighter: As one likely expect from a Sniper. Unlike all other weapons, sniper rifles are less accurate the closer the target is. The left side of the Sniper's abilities helps alleviate this weakness, but placing a Sniper right next to an alien still probably isn't going to work out that well.
A Combat Medic/Fire Support specialist with support skills like smoke grenades and the ability to carry more gear. They wield versatile assault rifles.
Combat Medic: The left side of their abilities emphasizes the latter word, the right emphasizes the former. For the former:
The Corporal "Covering Fire" passive ability allows Supports to activate Overwatch when enemies fire in addition to moving.
Lieutenant Supports can get the "Suppression Fire" active ability, elaborated in Pinned Down below.
The Colonel "Sentinel" passive ability allows the Support's Overwatch fire two reaction shots over the natural one.
Jack of All Stats: They tend to be average in most respects compared to the other classes, except movement speed if the Corporal "Sprinter" passive ability (increases Walking range by 3 tiles and Running range by an extra 3 tiles) is chosen. Their assault rifles also tend to be middle of the road in all stats. The "Deep Pockets" passive ability learned at Major rank also enhances their potential versatility to you.
The Medic: Several of their abilities emphasize this part of their job description:
The Sergeant "Field Medic" passive ability gives them 3 uses of the Medikit instead of just 1.
The Lieutenant "Revive" active ability lets them revive critically wounded soldiers at 33% of their max health instead of just stabilizing them.
The Colonel "Savior" passive ability increases the amount of damage healed by Medikits by 4.
When the Lieutenant "Rifle Suppression" ability is used, the Support's assault rifle tends to spew a lot of shots, even if it normally only fires a few rounds per attack.
The Colonel "Sentinel" passive ability lets them fire twice during Overwatch. Combined with the Corporal "Covering Fire" passive ability (which lets them shoot at firing enemies during Overwatch), they can fire off quite a few rounds when Overwatching.
Pinned Down: If the Lieutenant "Rifle Suppression" active ability is chosen, they can do this to any target of their choice for 1 turn. It does consume more ammo than firing normally, but it reduces the target's Aim by 30 and grants the Support a reaction shot should the target move.
Smoke Out: The base ability for the Support is a one-use-per-mission "Smoke Grenade" ability, which provides a defensive bonus equal to partial cover for all units in the smoke, allied or enemy. It can be further improved by choosing certain abilities.
The Sergeant "Smoke and Mirrors" passive ability lets the Support get another use per mission.
The Captain rank lets the Support get "Dense Smoke" (increased area of effect and increased defensive bonus equal to full cover) or "Combat Drugs" (all units in smoke also gain +20 Will and +10% Critical Strike chance) passive abilities.
Advanced weapons platform that can be deployed in place of a human soldier, they mount heavier weaponry than most soldiers.
Attack Drone: XCOM's personal ones, with a whole tech tree dedicated to them. They function exactly like the tanks of yore, including, in one case, functioning as portable cover. There are three varieties, Basic, Alloy (which can be used as low cover) and Hover (which can fly).
Beam Spam: S.H.I.V.s equipped with Laser Cannons, especially if they use their "Suppression" ability.
Crutch Character: Like the HWPs of old, they're better than the New Meat but lose out to high-rankers. Many strategies for Classic and Impossible involve rushing to get them into production ASAP.
Gatling Good: They start off with a minigun, which can be upgraded further.
XCOM soldiers who bear "The Gift", as the invading aliens call it, their psionic powers can turn the tide of battle. Any XCOM soldier could have the potential, though those with strong wills are more likely to have it.
All attempts to contact the invaders thus far have failed. Their only purpose seems to be destruction and chaos.
— News broadcast
These physically frail aliens serve as scouts for the invaders and appear to possess a telepathic ability unlike anything previously encountered on Earth. Individually weak, they are nonetheless dangerous in numbers, especially if allowed to utilize their ability to merge minds.
Reptilian aliens extensively altered to resemble humans, they are tasked with infiltrating human society to obtain information and conduct sabotage. They are capable of spitting out clouds of debilitating poison to weaken enemies and deny territory, as well as generating an identical cloud upon their death.
Face Death with Dignity: What does a Thin Man captive do when about to be interrogated? Ignore the torture equipment and stare his captors down as the blast door closes.
Hellish Pupils: Thin Men have reptilian eyes, hence why they all wear sunglasses to appear more human.
What Happened to the Mouse?: They disappear from the game altogether and are never mentioned again (even on the Temple Ship, which has you fight through every other enemy type in the game) after the attack on the Alien Base.
On the other hand, this does make sense. As they're more hardware than crew, them not being on the Temple Ship (which seems to be a base of operations and where all the aliens are coming from) fits.
A horrific fusion of flesh and machine, these cybernetic monstrosities bear integrated propulsion units, allowing them to take to the skies. The power of these units is such that they can rocket themselves anywhere on the battlefield, though they cannot immediately open fire after they land. The species is likely related biologically to the Mutons.
Fate Worse Than Death: Most of their organic parts were ripped out and replaced with machinery to effectively turn them into Living Weapons. The Uber Ethereal even uses the trope name word for word to describe them.
Vicious and nightmarish insect-like creatures, they seek only to propagate their species through implanting their eggs into a host's body. After a remarkably short gestation period, during which the host body is under the Chryssalid's control, a juvenile will burst out, ready to continue the cycle.
Attack Animal: They seem to be this, lacking apparent sapience but possessing a vicious instinct.
The invaders' front-line combatants, they are equipped with heavy armor and armaments. If struck by a non-fatal blow, they are very likely to roar their defiance at the firer, possibly intimidating them into submission. Their bloodlust and ferocity has not dimmed their tactical acumen, making them even deadlier foes. Probably related to the Floaters.
Pinned Down: They have the "Suppression" active ability, which reduces the target's Aim by 30 and grants the Muton a reaction shot should the target move.
These hovering weapons platforms provide heavy fire support for the invaders and are capable of shrugging off all but the heaviest attacks. Seemingly unarmed at first glance, they can rapidly transform to bring their many weapons to bear on an unfortunate target.
Silicon-Based Life: Stated to be something like a symbiosis between two species: one organic and one inorganic.
Transforming Mecha: They can transform between a nigh-invulnerable but unarmed disc form and a vulnerable but heavily-armed floating insect-bot form.
Small hovering drones, these accompany and provide support to the invaders' mechanical assets. Though their primary function is to repair, they also bear small energy weapons for self-defense and a self-destruct system to prevent capture.
The very first alien encountered by XCOM during Operation: Devil's Moon, these creatures appear to possess a terrifying capability of telepathically controlling human minds, as demonstrated near the end of the operation. They can be found directing the invasion from outposts and UFOs, as well as operating the systems of the latter.
Degraded Boss: Sort of. The first one you encounter is set up like a boss fight and you encounter increased amounts of them as regular enemies afterwards. However, they're just as strong as the first one.
Psychic Link: They have a stronger version of their lesser brethren's Mind Merge ability, called Greater Mind Merge. However, it only works with other Sectoids, which generally don't show up anymore once the Commanders do.
Even more ferocious and bloodthirsty than other Mutons, these hulking behemoths eschew the invaders' advanced plasma weapons in favor of pure brute strength, for devastating their enemies in melee. Their constant state of rage is such that any non-fatal blow will have them charge blindly at their enemy, allowing them to cover the distance quickly.
The Brute/Dumb Muscle: They'll always attempt to Intimidate and charge blindly towards those who have attacked them (often triggering reaction fire in the process), and have a very devastating melee attack.
Offhand Backhand: During Terror Missions, if a civilian is unlucky enough to be nearby it when a Berserker is first seen, the short video that plays when it comes into view involves the Berserker striding forward and offhandedly smashing the poor civilian's skull.
There Was A Door: One of the Berserker's abilities is being able to burst through walls to ambush your soldiers. Sometimes one will go out of its way to get behind a wall in preparation for this.
Wolverine Claws: Downplayed, they have a set of blades affixed to the back of their hands which extends to just in front of their fist, like extra-nasty knuckle-dusters.
The personal guards of the true leaders of the invasion, these veteran Mutons bear even heavier weapons and armor than their regular counterparts. Occasionally deployed independently of their masters, their mastery of combat makes them extremely dangerous opponents.
Massive war machines designed to utterly crush any opposition, these are the heaviest ground asset available to the invaders. Capable of withstanding incredible amounts of punishment, they also bear a deadly array of weapons to annihilate any who oppose it.
The true masterminds behind the invasion, these mysterious beings represent the pinnacle of psionic power amongst the invaders, compensating for their physical frailty. Their power is such that it is little wonder that the other aliens have submitted to their rule. They command from the safety of their specialized UFOs.
Not So Stoic: When interrogation starts, the Ethereal first looks at the machines passivly, but as soon as they're active it hunches over in pain and tries to deflect them psychicly before the doors close.
Psychic Powers: Uniquely, they can reflect normal attacks back at the shooter for 2 damage.