A former history professor, Tom lost his wife early on in the invasion, and he was left alone to keep his three sons safe. He joined the Massachusetts Militia with his sons, but his second oldest son Ben was captured and put into a harness when the invasion began, but was eventually rescued. Tom serves as Weaver's second in command of the 2nd Massachusetts.
- Action Survivor: In the first season. He becomes a warrior on his own from the second season onwards.
- Badass Beard: In contrast to Noah Wyle's other major TV role, Tom sports a fully-grown beard.
- Badass Bookworm: Taught college-level American History and is one of the best soldiers in the 2nd Mass.
- Beta Couple: With Anne. Tom might be the main character, but he has been in a stable relationship with Anne since the first season, while Hal and Ben have the major relationship drama in the show.
- Cultured Warrior: He is a history teacher, after all.
- Crusading Widower: The loss of his wife is a motivation for him.
- Eye Scream: An alien parasite gets removed from his left eye while he is still conscious.
- The Hero: He is the main character, after all. In time, the Resistance sees him as the best chance they have against the Espheni.
- Living Legend: According to Col. Porter, Tom is fast becoming one.
- Number Two: To Weaver in seasons 1 and 2. Inverted in season 3, Tom runs Charleston and Weaver is his loyal and most-trusted commander.
- Papa Wolf: Do not attempt to harm his children in any way. He won't take it well.
- President Action: Elected President of Charleston during the time-skip between seasons 2 and 3, Tom only agreed to take the job if they allowed him to keep leading the occasional combat mission. He allowed Arthur Manchester to keep running the day-to-day affairs of government.
- Properly Paranoid: After returning to the 2nd Mass after the aliens let him go, Tom insists that every keep an eye on him and stop him if he starts acting weird, due to his fears of brainwashing. The parasite in his left eye that Anne extracts that later escapes and goes to Red Eye shows his fears are not unfounded.
Tom's oldest son, Hal became a scout for the 2nd Massachusetts alongside his girlfriend Karen.
- Army Scout: His role in the 2nd Mass.
- Badass in Distress: Is taken hostage by Pope in Season 5.
- Battle Couple: With Karen for a while, and now with Margaret.
- Berserk Button: Don't even mention the name Karen to him...
- Brainwashed and Crazy: Implied as of the Season 2 finale. Confirmed in Season 3.
- Chick Magnet: He has had relationships with both Karen and Maggie.
- Deadpan Snarker: The snarkiest of the Masons.
- Easily Forgiven: No one except Pope gives him grief after his actions as the mole. Justified because he was under mind control, so it wasn't really his fault.
- Grand Theft Me: Gets infected by an alien implant at the end of Season 2, which takes over his body and leads him to try and kill Tom. Thankfully, he gets better.
- The Lancer: To his dad, and to Weaver during the three months in which Tom was missing.
- The Mole: Unknowingly for the Espheni or more specifically for Karen who is now one of the new overlords.
- Sexier Alter Ego: One of the first things Hal does when he is taken over by his implant is have passionate sex with Maggie.
- She's Not My Girlfriend: Says this of Margaret to Diego. He's not buying it.
- Ship Tease: With Margaret. It's developed into an Official Couple, though.
- Split Personality: Caused by Karen's Probe. Might be a case of Enemy Within, as the nature of the problem hasn't been properly explained.
- Superpowered Evil Side: His evil personality is quite stronger than his normal one.
- Trojan Prisoner: A variant on this in Season 1.
Tom's second oldest son, Ben was captured by the aliens and put into a harness while fighting for the 2nd Massachusetts. He was eventually rescued and freed from the harness, but is now suffering from some side-effects.
- Blessed with Suck: Being harnessed gave him various superhuman abilities (strength, senses, etc.) and the power to communicate with Skitters, but at the cost of putting stress on his muscular structure and possibly shortening his lifespan, and also causing him to be discriminated against by other humans.
- Blood Knight: In season 2 his main motivation apparently keeping the draw of the aliens at bay by focusing on his hatred for them.
- Took a Level in Badass: Thanks to whatever the harness did to him, he now has some enhanced abilities. He shows these off more in Season 2.
- Took a Level in Jerkass: In the season 2 premiere, though he gets better in later episodes.
- Translator Buddy: To Red-Eye and other aliens when needed. His remaining Skitter traits include their radio communication abilities, allowing him to translate what they're saying.
Tom's youngest son, Matt is too young to fight and stays at the camp with the rest of the civilians.
- Morality Pet: Shows signs of becoming one to Pope. Doesn't stop him from leaving, though.
- Took a Level in Badass: In Season 2 and again in Season 3.
A civilian doctor, Anne was a pediatrician before the invasion, and now does her best to treat the civilians and soldiers of the 2nd Massachusetts.
- Let's Get Dangerous!: Jury rigged a frakkin' flamethrower to deal with a bunch of nasty bugs.
- Outliving One's Offspring: Her son died at the start of the invasion. The trauma from losing him makes her determined to not lose Lexi.
- Team Mom: Always ready to provide emotional support to whoever needs it.
- Took a Level in Badass: See Let's Get Dangerous!. She took a few more after the 2nd Mass is scattered at the start of Season 4 and she takes command of a small group of fighters.
- Took a Level in Jerkass: Losing Lexi made her a very bitter woman.
- Unresolved Sexual Tension: With Tom.
- Seems resolved as of Season 2, Episode 6, with them together for now.
Colonel Daniel Weaver
A veteran of Operation Desert Storm, Weaver is placed in charge of the 2nd Massachusetts. He has little regard for the needs of the civilians with the unit, viewing them as a hindrance to fighting the aliens. He eventually grows out of this viewpoint and comes to rely heavily on Tom's advice.
- A Father to His Men: A harsh, tough father, but still
- Authority Equals Asskicking: As leader of the 2nd Mass. Tom Mason leapfrogs him by becoming President of Charleston in season 3 but Weaver remains his go-to guy for combat missions.
- The Captain: His official rank.
- Promoted to Colonel Badass in season 3.
- Control Freak: Called one by his daughter, though this mostly manifests as his Overprotective Dad status and someone pressing his Berserk Button (badmouthing him about his family). He admits he hasn't changed much.
- Cynicism Catalyst: Upon losing his wife and daughter, Weaver became the Jerk with a Heart of Gold we know today. His daughter, however, implies he was always like that.
- Death Glare: He practically communicates through those.
- The Determinator: You gotta hand it to a guy who is constantly injured, poisoned or under enemy fire. He never gives up.
- Heartbroken Badass: The loss of his wife weighs him down quite a bit.
- Heroic BSoD: Weaver goes through one of these after being exposed to one too many reminders of the family he's lost. He snaps out of it when he finds his wife's glasses and realizes she may still be alive.
- Hot-Blooded: Weaver isn't afraid to express his emotions.
- Jerk with a Heart of Gold: While a good person and primarily concerned with the good of the group as a whole, he tends to put the welfare and comfort of his fighters first.
- His Hidden Heart of Gold is best shown with his interactions with Jimmy, the 13-year-old fighter, whom he treats as a soldier and a child.
- Iconic Outfit: In-Universe. Margaret and Anthony joke in season two that his rugged jacket and hat are his trademark, and indeed, he's almost never seen without those.
- Knight in Sour Armor: World-weary and cynic, he remains a determined fighter for the 2nd Mass.
- The Leader: Type II for the 2nd Mass.
- The Lost Lenore: The loss of his wife (and daughter) made Weaver quite a bitter man.
- Made of Iron: Out of the entire main cast, Weaver is the one more likely to be poisoned, shot at, stabbed or be thrown through windows, yet he survives, every time. Lampshaded very frequently, such as Mason's off-hand comment that "Weaver is made of cast iron". However, these wounds are starting to take a toll on him, as seen by his recently discovered heart problems.
- Old Soldier: When the invasion started, his commission in the Army was reactivated. He's a career soldier before the invasion. Even when Tom becomes de facto leader of the 2nd Mass, Weaver is still at the forefront of every battle.
- Reasonable Authority Figure: Eventually gets to this point.
- Sanity Slippage: In "Mutiny". He got better.
- Suffers a more severe one in season four. He's still sane, but he's..off.
- Shell-Shocked Veteran: Weaver was quite psychologically damaged by the conflict. He has on hell of a Thousand-Yard Stare.
- Tragic Keepsake: If you look carefully, you'll notice his hand has a small band wrapped around it. That band belonged to his now deceased wife.
- Trauma Conga Line: The universe just seems to pile up misery after misery on him. He lost his wife, accidentally killed his younger daughter, is frequently on the brink of death, acquired severe heart problems and has now watched his older daughter be turned into a monster and die before his eyes.
A scout with the 2nd Massachusetts, Karen is dating Hal. She is captured by the Skitters during the rescue of Ben and put into a harness. She later returns as the mouthpiece of an Overlord who talks with Tom.
- Action Girl: She was Hal's partner in scouting missions.
- Dark Action Girl: After becoming an Espheni pawn, she becomes more ferocious and terrifying.
- Alas, Poor Villain: Played with. In her final moments, she apologized for her actions and confesses her love to Hal, but we have no clue if she was being sincere or not, and no one except Hal seems to believe her words (specially Margaret, who actually shoots her mid-sentence).
- Army Scout: Her position in the 2nd Mass.
- Battle Couple: With Hal for a while.
- Big Bad Friend: Seems to be heading towards this direction as she now serves as the Overlord of eastern North America replacing the previous one killed by Tom.
- This is no longer the case as of the Season 3 finale, where she's finally killed.
- Biker Babe: She used a bike in scouting missions.
- Brainwashed and Crazy: Thanks to the harness, although she tells Tom that she is still the same girl he knew. He doesn't buy it, and she later admits that the old Karen is dead.
- Clingy Jealous Girl: Automatically suspected Lourdes of coming on to Hal when the other girl was being friendly.
- Does This Remind You of Anything?: Her reaction to putting her harness back on.
- Mouth of Sauron: The Overlord speaks through a psychic connection with her.
- Softspoken Sadist: Very much so, especially every time she tortures someone. Also sports a Creepy Monotone.
- Super Strength: After being harnessed, she can lift a bed and throw Maggie into a wall without any noticeable effort.
- Villain's Dying Grace: By accident. She releases Anne and Lexie (who were previously thought to be dead) as a token of peace towards humanity, but unexpectedly Tom shoots her dead mid-way through the conversation, and as a result her final act is releasing Anne and Lexie.
- Would Hurt a Child: Admits to Tom that she would hurt Tom's newborn daughter to get the necessary information.
Margaret (aka "Maggie")
An unwilling member of Pope's band of marauders, Margaret helped the captured members of the 2nd Mass escape and kill them. She then joined Tom's squad, and quickly grew close to Hal.
- Action Girl: Seriously shown in the season three premiere, where she takes on three harnessed kids by herself and when she runs out of ammo, charges at the next one with her knife.
- Broken Bird: Due to her rape by Pope's brother (and other gang members), not to mention the general crapsackiness of the world's current situation. She also had cancer when she was 16.
- Dark and Troubled Past: She slowly opens up to Hal about her past, and it is all tragic and messed up.
- Defrosting Ice Queen: Non-romantic with the entire group over time (and somewhat romantically with Hal), starting with how she treated Jimmy during an attack.
- Despair Event Horizon: She seems to have crossed it when she had cancer. After she was cured, she could only see the world as fake. It's unclear if she's come back yet, but her rape probably didn't help.
- Empowered Badass Normal: After getting some of Ben's spikes, she gets the powers of the semi-harnessed for herself.
- Ship Tease: With Hal. They have an entire conversation about Skitter reproduction that ends with him asking if they're still talking about Skitters once she brings up polygamy. They become an actual couple in Season 3.
A religious member of the 2nd Mass who was in pre-med before the invasion, and now serves as an assistant medic to Anne.
- Break the Cutie: In season two, starting with her learning that the area of Mexico in which her extended family lived had been destroyed, and continuing when Jamil is killed. Her subsequent brainwashing into The Mole probably didn't help.
- Despair Event Horizon: Her positive outlook on life is shattered after Jamil dies, not long after she learns that her family is likely dead. She gets better, though.
- HeelFaith Turn: Inverted Trope in Season 4. Finding religion with Alexis leads to her becoming a tyrant in her community, discouraging anyone from associating with her. Margaret is not willing to take her crap, and Ben can also get through due to being Alexis's brother and trust framework.
- Jade-Colored Glasses: Puts them on after Jamil dies
- Killed Off for Real: Murdered by Lexi, which she claims is "setting her free."
- Mercy Kill: How Lexi interprets her murder of Lourdes. It's quite clear this isn't the case.
- The Mole: She's been infected by an Espheni probe, but it gets cleaned out by Season 3's end.
A soldier with the 2nd Massachusetts, Dai is good friends with Tom. He considers himself lucky to have no family, since it means he did not lose anyone close to him in the invasion.
- Advertised Extra: After a lot of involvement in Season 1, his role is reduced in Season 2, and then he was killed in the finale.
- Bring News Back: He was visiting HQ to get order from Porter when it was attacked, and was sent back to the 2nd Mass with orders and information while Col.Porter and his men bought him time to escape.
- The Lancer: To Tom, when Hal isnt around.
- Number Two: Though he and Hal both act as the Lancer, Dai seems closer to this role for Tom.
- Third-Person Person: In "Grace", when he's "high as a freakin' kite".
A former Boston cop and a member of Toms team.
- Friendly Sniper: His bio on the series website notes he is one of the best shooters in the 2nd Mass.
- Put on a Bus: Leaves to keep an eye on Pope when he deserts the 2nd Mass after the incident with Jimmy's compass.
- The Bus Came Back: In Season 2, Episode 6, along with Pope.
- Number Two: To Anne after she becomes leader of a resistance force when the 2nd Mass is scattered at the start of the fourth season.
- Out of Focus: Gets a bad case of this in season 4.
- Sanity Slippage: He's starting to lose his shit in season 5 thanks to Denny's death. It leads to him betraying the group and joining Pope's gang.
- Vitriolic Best Buds: Starting to develop this with Pope, though he will still side with the rest of the 2nd Mass in an argument against Pope. Plus he hasn't forgiven him for the fact that one of Pope's marauders killed his friend Click, but also notes that Pope saved his life back in Boston, so he is not sure what to make of Pope.
The leader of a gang of racists and rapists, John captured Tom and his squad in an effort to get the 2nd Massachusetts .50 caliber machine gun and food stores, but failed and was captured by them. He has since joined up with the 2nd Mass as the leader of a squad called the Berserkers who shared his bloodlust and hatred of the Skitters.
- Anti-Hero: Type IV, bordering on Type V. Crosses the threshold in Season 5 and becomes a full-on villain.
- Bald of Evil: Shaves his head and grows out his beard when he becomes a true villain.
- Better to Die than Be Killed: Inverted. When it's clear that he's done for, he hands Tom his revolver and calmly begs him to finish him off. He's genuinely pissed off when Tom refuses, leaving him to a natural death shortly thereafter.
- Big Bad: One of two in Season 5, alongside the Espheni Queen.
- Blood Knight: Don't make him choose between killing Skitters and anything else. You might regret it.
- Dropped a Bridge on Him: Suddenly dies from injuries incurred in the penultimate episode during his last confrontation with Tom.
- Dude, Where's My Respect?: It doesn't matter what he does, how friendly he is, or how often he saves Tom's life, Tom is consistently an ass to him. It doesn't help that he has proven himself as an effective leader during Tom's absence, yet he's rarely listened to or given any input on the 2nd Mass' plans once Tom comes back. This is one of the factors in his FaceHeel Turn.
- Even Evil Has Standards: He is disgusted by the fact that some humans actually make deals with the Skitters.
- FaceHeel Turn: Goes completely insane after Sara is killed, deserts the 2nd Mass, and declares war on Tom.
- Hidden Depths: He's a surprisingly good chef, and seems very well-read.
- Karmic Death: Takes a series of gas explosions head-on while trying to destroy the 2nd Mass, and survives long enough to have Tom refuse to give him the satisfaction of being shot.
- Last-Name Basis: To the point that it's hard to remember his first name is John.
- The Nicknamer: He almost never uses anyone's real name, preferring to give nicknames such as:
- Tom Mason: "Papa Smurf".
- Karen Nadler: "Sexy Freedom Fighter Girl".
- Hal Mason: "Strapping Young Man".
- Anthony: "Black Gangbanger".
- Dai: "Oriental of Some Sort".
- Weaver: "El Capitan", and "Supreme Allied Commander of the 2nd Massachusetts".
- Margaret: "Little Miss Midwife With A Heart Of Gold".
- Matt Manson: "Little Prince Of The 2nd Mass".
- Ben and Hal: "Little Princelets"
- The Only One Allowed to Defeat You: To Tom.
- Only Sane Man: He's not, but he tends to think he is.
- Papa Wolf: Followed after a guy who nearly ran his son over. Wound up accidentally killing him, and landed behind bars.
- Pet the Dog: Becoming the chef for the resistance.
- Post-Final Boss: Shows up one last time after Tom defeats the Espheni Queen and ends the war.
- Put on a Bus: Willingly leaves the 2nd Mass after the incident in which he stole Weaver's compass off of Jimmy's corpse because he could.
- The Bus Came Back: In Episode 6, Season 2, he returns to the 2nd Mass in order to warn them about Ben and the truth of the Skitter rebellion. He stays with them for the remaining seasons.
- Reasonable Authority Figure: In season 3, he turns into one for the group of soldiers he commands (as demonstrated by his scene with Lars).
- Sixth Ranger
- Sixth Ranger Traitor: In Season 5.
Alexis "Lexi" Glass Mason
The daughter of Tom and Anne, who is born in Season 3. From the start she shows signs of rapid aging and strange abilities. By season 4 she has grown into a teenaged girl, and is seen as the messiah by many and a threat by others.
- Ambiguously Evil: She's hard to predict from the start, but ultimately settles on the side of good in the end.
- The Atoner: Becomes this by the end of season 4, especially for killing Lourdes.
- Creepy Child: Especially as a baby and young child.
- Death Equals Redemption: Though she had already redeemed herself in Tom's eyes, her heroic death clinched it.
- HeelFace Turn: After overhearing the Monk and Scorch plotting to kill her.
- Heroic Sacrifice: Blows herself up to destroy the Espheni power core.
- My God, What Have I Done?: After realizing the Monk's true nature, she expresses horror at her actions.
- Physical God: She can shape reality itself to her own will.
- Rapid Aging: Ages from a baby into a fully grown woman in the span of a few months.
- Reality Warper: The Monk makes note she may become this.
A 13-year-old soldier who fights with the 2nd Mass.
- Impaled with Extreme Prejudice: A branch to the gut pins him to a tree in a Skitter hunt, killing him.
- No Sense of Direction: Said word for word by Weaver while giving Jimmy's eulogy. He gave Jimmy his compass after he got lost for two days while on patrol.
Colonel Jim Porter
The overall leader of the Massachusetts Militia. Later become's one of the commanders of the 1st Continental Army based out of Charleston, South Carolina.
- Dropped a Bridge on Him: After being a fairly major character, he seemed to have been Killed Offscreen in the first episode of season four, never to be mentioned again.
- Never Found the Body: Dai was visiting headquarters when it was attacked, and brought word back to the 2nd Mass that Porter was leading a last ditch defense. All contact was lost with command after this, and Porter was assumed to be dead. He's revealed as alive in Season 2, and in Charleston.
- Typecasting: Have you ever seen Dye play a non-military character? Justified since he actually was a Marine captain in Vietnam.
- What Happened to the Mouse?: In season four, as the Overlords bomb the 2nd Mass and build the ghetto around, he disappears. He is also never mentined after that. It's likely he died.
Annes uncle and a biology teacher. He also serves a technician for the 2nd Mass.
- Dropped a Bridge on Him: He and his wife died in the three month gap between seasons 1 & 2.
- No Kill Like Overkill: He was apparently "torn apart" by mech bullets according to Ben.
A member of the 2nd Mass who is best friends with Anthony. Killed early in season 1 by Pope's mauraders.
- Forgotten Fallen Friend: Averted. Early in Season 2, Anthony mentions to Pope that he has not forgotten that Pope and his men killed Click.
Doctor Michael Harris
A medical surgeon and old friend of Tom.
- Asshole Victim: Murdered by the Skitter he tortured.
A soldier for the 2nd Mass whose son was harnessed.
Mike's formerly harnessed son, but he is none too happy about being freed.
- HeelFace Door-Slam: It doesn't help his mortality however.
- Put on a Bus: Anne tells Tom that Rick disappeared sometime during the three months he was missing.
- The Bus Came Back: Came back for episode five of season 2.
- Stockholm Syndrome: Seems to have gotten over this by Season 2, for the most part.
- Taking the Bullet: Took a shotgun blast to the chest for Red-Eye.
Lieutenant Terry Clayton
Leader of the few surviving members of the 7th Mass, he kept his group alive by giving children to the aliens.
Jamil is the 2nd Mass' head engineer and vehicle technician, and is in a relationship with Lourdes.
- Eaten Alive: From the inside out.
- Remember the New Guy?: Though he may have joined after Season 1.
Aloysius "Tector" Murphy
Tector is a former Marine Gunnery Sergeant who joined Pope's Berserkers. He forms a friendship with Captain Weaver, who helps him recover his confidence and military discipline.
- Fake Guest Star: Tector's gotten more screentime than Dai and a few other main characters in Season 2 and has one of the more fleshed out backstories among the characters.
- Heroic Sacrifice: He takes Mason's place and disguises himself as him to save him from the Overlord's wrath.
- My Greatest Failure: While serving in the Marines, Tector led his squad into an ambush that resulted in three of his men dying, and he blames himself he didn't properly look at the map of the area they were going to patrol and realize how dangerous the terrain was. When Boone gets killed, he blames himself again since he had been training Boone.
- Nice Guy: Espically when compared to the rest of the Berserkers.
- Number Two: To whoever is leading the Berserkers.
- Taking You with Me: Suicide bombs himself after acting a distraction for Scorch.Tector: Tick, tick BOOM!
"Crazy" Lee (Luciana Carro), Lyle (Brad Kelly), and Boone (Billy Wickman)
The Berserkers are a squad founded by Pope which consists of several members of the 2nd Mass who share his hatred of the aliens. They are usually given assignments which other squads consider too crazy to consider doing. Led by Tom Mason after his return to the 2nd Mass.
- Ascended Extra: Lyle has a lot more screen-time and dialogue in season 3. Probably as a result of the two other main Berserkers dying.
- Attack! Attack! Attack!: Lyle's idea of a good strategy.
- The Big Guy: That's roughly their role within the 2nd Mass ranks. Amongst their own ranks, Lyle.
- Boisterous Bruiser: All of them (particularly Lyle), with the exception of Tector and Pope.
- Blood Knight: All members of the Berserkers share Pope's fondness for killing Skitters.
- Breaking the Fellowship: In season four the Berserkers cease to exist. This is because all of their members are dead or split apart.
- Deadpan Snarkers
- Dropped a Bridge on Him: Lyle inadvertently walks into a laser field and is promptly turned into a mush of blood. This is never mentioned again.
- Dwindling Party: The Berserkers are dying off season by season.
- Friendly Snipers
- Hidden Depths / Smarter Than You Look: At one point, Anthony wonders "What are they waiting for?", Lyle, whose dialogue thus far has consisted of threats or nods of agreement, answers "Godot.". Even Anthony seems surprised by the answer.
Jeanne is Weaver's oldest daugher, who he is reunited with on the road to Charleston.
- Action Girl: Is just as fight-prone as her father.
- Fighting from the Inside: She fought against the Espheni brainwashing like this.
- Half-Human Hybrid: Her ultimate fate.
- Heroic Sacrifice: She dies fighting a Skitter to protect Weaver.
- Nice Girl: While her father stands in the realms of Jerk with a Heart of Gold, she's more polite.
- Sacrificial Lion: She's turned into a human-Espheni hybrid, which displays the effects of this transformation to the characters and the audience, as well as giving Weaver more emotional wounds.
Arthur is Tom's former mentor and the "majority leader" of Charleston's civilian population.
- Broken Pedestal: He used to be Tom's teacher.
- Drunk with Power: A mix of this and Well-Intentioned Extremist
- He Knows Too Much: Was getting close to finding out who the mole was in the season 3 premiere which resulted with his death by the hands of The Mole.
- HeelFace Revolving Door: Starts off as a hero, quickly drifts into villain, then kicks back to hero.
- Sacrificial Lion: His death signals how serious the spy problem is.
- Shadow Archetype: Shares Mason's love for American history, his intellect, commands in a similar manner, but is somewhat more flawed.
- Well-Intentioned Extremist: He only seeks the best for mankind's future.
Brigadier General Cole Bressler
Bressler is the commander of Charleston's military forces.
- Ace Pilot: Quite a skilled pilot, apparently.
- Commander Contrarian: Amongst the military leaders of season 3, his job consists of trying to counter-argue everything the other three say.
- Dropped a Bridge on Him: Dies in a plane crash without any warning.
- Fantastic Racism: Against all alien lifeforms.
- Heroic Sacrifice: of a sort. His piloting skills are what saved Mason and Pope, but he dies in the crash.
An unharnessed girl who fights alongside Ben and the Skitter Rebellion. After the resistance is scattered at the start of Season 4, she is a member of Anne's group.
- The Big Girl: Thanks to her powers, she can take and dish out more damage than most other members of the resistance.
- Cruel and Unusual Death: Torn apart by skitters.
An aide to Tom after he becomes President of Charleston.
- Number Two: For Mason's presidency.
- Reasonable Authority Figure: When Mason leaves Charleston and she's temporarily in charge, she becomes this.
- Unresolved Sexual Tension: Appears to have some with Col. Weaver.
- What Happened to the Mouse?: She isn't seen in Season 4 after the Espheni attack on Charleston separated the survivors. She was probably killed when the city was attacked or taken to another ghetto.
Dr. Roger Kadar
Kadar is an agoraphobic scientist in charge of keeping power in Charleston running.
- Attention Deficit Oh Shiny: He suffers from this whenever talking to Weaver.
- Bunny-Ears Lawyer: While his conversations make no sense whatsoever, he's one hell of a nuclear scientist.
- Cynicism Catalyst: It is heavily implied by the way talks about children that he once had a child, and that its death was what caused his current Hikikomori way of living.
- Dying Speech: He makes one to Mason.Kadar: "Is this it? I was a walking dead man when you found me anyway. Dr. Glass, Lexi's samples. I wasn't able to save her, maybe someone else can. (...) I never told you, Lexi has the same color eyes as my daughter. Just tell her I wasn't able to do more for her, and I'm sorry. To you, Tom, don't you let her go again! You'll find away. And you...you bring her back."
- Face Death with Dignity: Kadar remains calm and collected as he takes his last breath.
- Hikikomori: Though his case seems a little more justified, since there is a war going outside.
- Major Injury Underreaction: Doesn't even a notice a piece of shrapnel in his side until Weaver points it out. Slightly lampshaded when he mutters "You'd think that would hurt." He promptly bleeds to death.
- Outliving One's Offspring: He had a daughter before the Espheni invasion. How she died is unknown.
- The Smart Guy: The main source of advanced scientific explanations in Charleston.
A man who joins the 2nd Mass after helping break Tom and company out of an Espheni ghetto.
- Action Girl: Subverted. She's not as hardened as she appears to be, as shown by her reaction to the countless deaths when the 2nd Mass is attacked in Season 4.
- Belligerent Sexual Tension: With Pope. Acknowledged in Season 5, and they almost become an Official Couple before she is killed.
- Changed My Mind, Kid: Deserts the group after an argument with Pope, but returns in the finale just in time to save Pope and Dingaan's lives.
- Cruel and Unusual Death: After getting stuck in some leftover alien fog, her legs are eaten off by Espheni bugs. Pope comes back to save her just in time to watch her die.
- Deadpan Snarker: She and Pope hit it off almost immediately because of this.
- Died in Your Arms Tonight: She dies in Pope's.
- The Lost Lenore: For Pope.
- Morality Chain: Becomes Pope's. Her death causes him to snap completely.
More commonly known as "Team Leader", he is the teacher of a re-education camp in Charleston.
- Asshole Victim: It's hard to feel sorry for a man who gave his own mother up to the Espheni.
- Back for the Dead: He's absent for several episodes after getting beaten up by Tom, and is killed in the one he returns in.
- A Nazi by Any Other Name: The camp he runs has obvious similarities to the Hitler youth, up to and including the practice of reporting family members with dissenting opinions.
- Would Hurt a Child: Has no problem with giving up children to the Espheni, and attacks Matt when he catches him trying to escape from the camp.
- No-Holds-Barred Beatdown: Ends up on the receiving end of one from Tom when he attacks Matt.
A girl who Matt meets in the Charleston re-education camp. She assists him in his attempts to escape.
- Brainwashed and Crazy: Scorch harnesses her and uses her as a mouthpiece in the season 4 finale.
- FaceHeel Turn: After being left behind by Matt at the camp, she was indoctrinated by Kent and sells out Matt the moment she sees him.
- Killed Offscreen: Her most likely fate when Lexi blew up the Espheni power station.
- Puppy Love: With Matt.
The Espheni Empire
A member of the alien race that invaded Earth who temporarily held Tom.
- Alien Blood: In his case in particular, he seems to bleed dark blue.
- Big Bad: Or at least a member of the species of Big Bads.
- Blade Below the Shoulder: Whips them out against Tom and the rebel Skitters. While they kill Red Eye, Tom isn't hurt.
- The Chessmaster: If you re-watch series two carefully, you'll notice a considerably large chunk of its events were part of the Overlord's plan. In particular Karen's entire participation
- The Corrupter: Regarding Karen, at least.
- Evil Cannot Comprehend Good: He doesn't seem to grasp why Mason dislikes the idea of living in a reservation for the rest of his life.
- Faux Affably Evil: Acts remarkably polite and soft-spoken, but no less despicable.
- Galactic Conqueror: His species has a knack for enslaving sentient species under any means necessary, and are shown to have done this at least once before, with the Skitters. Curiously, he's called "Overlord" In-Universe.
- In-Series Nickname: For his entire species, which the Resistance calls Overlords, or more derisively, "fish heads". The Season 2 finale gives the actual name of the species.
- Lack of Empathy: Discussed. According to him, it's his main strength.
- Last Villain Stand: Decides to face the Skitter army and the Second Mass head-on, despite being outnumbered and outgunned.
- Light Is Not Good: The Overlords look remarkably white and bright. Don't be fooled by that.
- The Man Behind the Man: A member of the species apparently controlling the Skitters.
- Non-Action Big Bad: A bullet can seemingly kill him and he never fights.
- His first attempt at hand to hand combat is his last, as Tom effortlessly kills him.
- No Name Given: We don't even know if his species use names, but if nonetheless we are never given a name for him, and so he's called by a wide variety of nicknamed (The Overlord, Fishhead, Espheni and so forth)
- Straw Vulcan: He goes on a lengthy dialogue with Mason explaining how humanity's greatest strength is also their greatest weaknesses: Emotions. According to him, mankind's attachment gives them strength, but also leads them to trouble. To prove his point, he almost kills Tom's son. Mason shoots him. Which proves his point.
- Super Intelligence: According to Red Eye, all members of his species have Photographic Memory and Hyper-Awareness.
- Villain Takes an Interest: After Mason shot down one of the Drones.
- The Voiceless: In the literal sense of the word, his species seem to be uncapable of communicating in human tongues and Skitter tongues, they communicate through telepathy or...
- Mouth of Sauron: ...Harnessed humans and Skitters.
- Wicked Cultured: Knows a lot about our history and philosophy.
- Humans Are the Real Monsters: His judgment of humanity as a result after cherry-picking the worst examples.
Another high-ranking Espheni, tasked with overseeing the South Carolina Ghetto. He appears to be older than the previous Espheni, and a lot more dangerous.
- An Offer You Can't Refuse: Uses this tactic very freely.
- Bond Villain Stupidity: He was so focused on killing Lexi, he ignores a downed Tom who is right behind them, unaware he has a poisoned syringed that can kill him.
- Cassandra Truth: He tells The Monk Lexi will rebel and disrupt all their plans, but he's ignored.
- The Chessmaster: Already shows a high-degree of skill at playing against Tom Mason, and judging by the way he talks, he seems to have a few cards up his sleeve.
- Deadpan Snarker: Scorch takes a few, subtle verbal jabs at Mason when they talk.
- Didn't See That Coming: Tom's syringe blindsided him entirely.
- Evil Old Folks: Possibly. If you compare him to the other Overlords, you will notice his skin is far more wrinkled, maybe implying age.
- Exact Words: Mason commands him not to touch his daughter. Scorch smugly retorts he doesn't need to.
- Frontline General: He is seen leading his troops directly to battle Mason, a first for the Overlords.
- I Have Your Wife: Threatens Mason with this.
- Last Breath Bullet: Not literally, but as Scorch lays dying he rips out the self-navigation system of his ship, essentially forcing Lexi to sacrifice herself.
- Made of Iron: Survives being pretty much roasted alive.
- Meet the New Boss: The promo that introduced him mentioned this exact phrase.
- A Nazi by Any Other Name: Institutes ghettos like those from World War II and uses kidnapped children in a Hitler Youth-style "New Coalition" reeducation camp. Matt explicitly mentions the parallels on the latter. Interestingly, these are the exact behaviors the first Espheni leader in the show used as an example of the worst of humanity.
- Knight Templar: He is apparently gathering an army to fight a larger threat of some kind.
- Only Known By His Nickname: "Scorch" is all we've got.
- Roaring Rampage of Revenge: Being roasted alive didn't make Scorch any friendlier with Mason. Mason himself makes note that Scorch is going to destroy everything until he finds him.
- Sinister Surveillance: Scorch is always watching with a billion eyes.
- Spanner in the Works: His interference forces Lexi to sacrifice herself to destroy the power source.
- Taking You with Me: Probably why he ripped off the ship's navigation device.
- The Evils of Free Will: "Free will can be dangerous, but I don't have to tell you that." Says Scorch, towards Mason.
- 24-Hour Armor: He wears some sort of thick steel armor all the time.
- Vagueness Is Coming: He warns Mason a greater evil is on the way, but he never specifies what exactly he's talking about. It is justified by the fact Mason isn't his ally and he has no reason to share intel with him.
- Wardens Are Evil: We are talking about a Nazi-style ghetto of innocent people rather than an actual prison, so this trope applies in full force.
- Well-Intentioned Extremist: In his own words. The entire Espheni invasion is apparently just to gather resources to fight off a greater evil of some kind.
An unnamed Espheni, always wearing a cloak, provides guidance to Lexi for unknown purposes.
- Black Cloak: He wears one at all times, probably to make it easier for him to sneak around.
- The Chessmaster: If his dialogue with Scorch is any indication, he's playing a long game on humans for unknown purposes.
- We eventually learn that he's manipulating Lexi into using her powers for destructive purposes.
- Deader Than Dead: Lexi disintegrates him.
- Deadpan Snarker: His conversation with Scorch is full Snark-to-Snark Combat.
- Hidden Agenda Villain: His motivations are completely in the dark. Near the end of the season we finally learn that he's trying to turn Lexi into a weapon.
- Hoist by His Own Petard: Lexi kills him with the powers that he taught her to use.
- No Name Given: He's been nicknamed "The Monk" due his robes and quasi-religious role to Lexi.
- Psychic Powers: The Monk seems to posess several psychic abilities, namely telepathy and some form of telekinesis.
- Sibling Team: Scorch and the Monk call one another "Geminus", which is latin for "Twin". It's possible they are brothers.
- Twin Telepathy: They communicate telepathically.
- God Save Us from the Queen!: She is the queen of the Espheni, after all.
- Greater-Scope Villain: She was behind everything, the Overlords and Karen were her proxies.
- Hoist by Her Own Petard: She attempts to drain Tom of his blood but Tom had already injected himself with the Dornia weapon. His altered blood kills her.
- Hypocrite: The first Espheni overlord captured by the 2nd Mass argued the Espheni were devoid of emotions, and thus were superior to humans. In the finale, the invasion was ordered by the queen because she was enraged that her daughter was killed by primitive humans.
- Karmic Death: Killed in the finale by a weapon created by her ancient enemy, the last Dornia.
- Revenge: She hates humans because her daughter was killed by primitive humans 1,500 years before the modern age.
- Walking Spoiler: The fact that the Espheni even had a queen was only revealed in the final episodes.
A Skitter aboard the ship Tom was temporarily held on. He followed the humans, was captured, and tells the humans through one of the rescued children that he's part of a Skitter resistance. Current location unknown, as he escaped in the attempt by Ricky and Ben to free him.
- Big Damn Heroes: Saves the 2nd Mass strike team sent to destroy the Overlord's weapon, but dies fighting the Overlord.
- Dragon with an Agenda: Appears to be The Dragon to the Overlord that Tom saw, and is actually the leader of the Skitter resistance.
- Fighting from the Inside: He and some of the other skitters have been able to resist the harnesses.
Spokesman and member of the Volm species first introduced at the end of season two. Serves as a liaison with the human resistance in Charleston.
- Aliens Speaking English: The first alien in the series who can speak English without having to speak through a harnessed human.
- Ambiguously Evil: Speculation on their true objectives have been a great concern in the 2nd Mass. Turns out to be subverted.
- The Comically Serious: Cochise's overly formal way of speaking can be quite amusing at times.
- Fighting for a Homeland: However, he doubts he will ever get to see his homeland on his lifetime, commenting that he fights so the children of his children might see it.
- First Contact: His introduction in the finale of season two mirrored many classic examples of such scenes - aside from the fact that Earth was already crawling with other alien species...
- Healing Factor: When seriously wounded he heals on his own without need for medical attention.
- I Come in Peace: Cochise and the other Volm are aiding the human resistance as of the beginning of season three, though many people are wondering whether they will turn out to be a case of We Come in Peace Shoot to Kill. They don't, even though the species-wide alliance is almost soured in the season finale, and Cochise is still helping the 2nd Mass out.
- Ill Girl: Almost reaches the end of his lifespan in Season 5 due to organ failure, but is saved at the last second by his father's donation.
- Meaningful Name: Named after Indian resistance fighter Cochise.
- My Country, Right or Wrong: "Like you, Colonel, I am a soldier. I follow orders, whether I agree with them or not." Says Cochise, regarding his orders to relocate 2nd Mass against their will. He changes his mind, though, and becomes a steadfast ally of humanity.
- Officer and a Gentleman: Looks like this thus far.
- The Stoic: Always cool-headed.
- Not So Stoic: His voice cracks up briefly when he is talking about his (deceased) brother, and he sheds tears after his father dies.
The Volm in charge of the entire Volm expeditionary force on Earth, and Cochise's father.
- Acting for Two / Talking to Himself: Doug Jones not only wears the make-up for both of them, but he also voice-acts them both (only with a digital enhancement for Waschak).
- Big Damn Heroes: In the finale of season four, he comes guns blazing to save Mason from a Beamer squadron.
- Big Good: For the Volm. Not so much for humanity
- Commanding Coolness
- Hero of Another Story: He's been waging another, much larger and deadlier, war against the Overlords off-screen in the present, and in the past, he fought them across several planets.
- Humanity Is Insane/Humans Are Warriors: Seems to conflate the two because humans are the first race he's encountered who weren't happy to let his people do their fighting for them and go to a reservation
- My Country, Right or Wrong: Same deal as Cochise, he just follows protocol whatever it may be.
- Old Soldier: His voice, appearance and implied history (being the father of the already adult Cochise) give him the feel of this trope.
- Put on a Bus: Largely absent from season four due fighting in other theaters of the war.
- The Bus Came Back: In the finale.
- Reasonable Authority Figure: Zig-zagged a bit but ultimately played straight.
- The Strategist: Implied to be the mind behind the entire Volm offensive that turned the tide of the war.
- Well-Intentioned Extremist: He (at first) forces humans to go to a reservation, but simply so they won't be in harm's way. He genuinely wants the best for mankind.
Shak-Chic Il She- Shesash
Cochise's right-hand-man and trusted confidant. Dislikes humans.
- Fantastic Racism: Shows signs of it towards humanity.
- In-Series Nickname: The human characters shorten his name to "Shak," sounding just like "Shaq," the nickname of basketball player Shaquille O'Neal. This references Shak's great height (De Santis is 6' 9").
- Teeth-Clenched Teamwork: He appears to hold a heavy dislike towards humans, and only fights alongside them because he's ordered to.
A mysterious alien who picks Tom up at the end of Season 4. It takes the form of his dead wife to speak to him, only occasionally showing glimpses of its true form.
- A Form You Are Comfortable With: It usually appears as Tom's deceased wife, Rebecca. This doesn't exactly make him comfortable.
- Big Good: It's been manipulating events for a while to turn the tables on the Espheni.
- The Chessmaster: By its own admission, it functions by analyzing potentially useful assets, then pushing them into the playing field precisely when they will be most useful for the cause.
- Deus ex Machina: Often plays this role, most obviously when it rescues Tom in Season 4 and brings Anne back to life in the series finale.
- Last of His Kind: Every other Dornia was turned into a Skitter.
- Starfish Aliens: Its abilities are unlike any other being in the series, and what little we see of its true form is... strange.
- Walking Spoiler: Saying anything about it spoils a big part of the final season.
- You Cannot Grasp the True Form: It would be impossible to communicate with Tom in its base form, at least.