Borderlands includes four character classes, each with unique skills, abilities and back stories. As a character gains experience and levels up, their basic statistics, such as health totals and accuracy, will increase. Each class also has three unique focus skill trees to develop. There is also an accessory item type specific to each class. The four classes are:
- Mordecai - The Hunter, who has skills that enhance sniper rifles and pistols. He sends his pet Bloodwing to attack enemies from above. 'Bloodwing' is an AI-controlled aerial unit that will operate semi-independently of the hunter.
- Sniper tree: improves sniper abilities;
- Rogue tree: improves special ability.
- Gunslinger tree: improves pistol and melee abilities.
- Roland - The Soldier, who is well suited to using combat rifles and shotguns. He can deploy an automatic Scorpio Turret to attack enemies, which operates independently, allowing the soldier to hide behind cover or attack enemies while his turret attacks enemies.
- Infantry tree: increases effectiveness with weapons; particularly combat rifles and shotguns.
- Support tree: increase Roland's defensive abilities with shields, and improve his Scorpio Turret's cooldown, increases its burst fire count and allow his turret to support the Soldier and his teammates by constantly resupplying their ordnance.
- Medic tree: abilities that allow the Soldier to rapidly replenish his health and his allies' even in the midst of heavy combat.
- Lilith - The Siren, who has advantages using SMGs and Elemental weapons. Touched by ancient alien power, her ability is Phasewalk: She can shift into a different dimension and become invisible for a few seconds, and when she enters or exits that state she releases a shockwave of energy which damages nearby enemies.
- Controller tree: improves survivability and disables foes.
- Elemental tree: improves her ability to use weapons and inflict Elemental damage.
- Assassin tree: increases lethality with weaponry and melee combat.
- Brick - The Berserker, who loves to do nothing more than pound enemies with his fists. Other than that, is a master of blasting his foes with explosive heavy weapons. His ability is 'Berserk', in which he uses his fists to pound his enemies to death, and gains large increases to his survivability and speed to achieve that end.
- Brawler tree: increases melee damage capabilities.
- Tank tree: massively increases toughness and survivability.
- Blaster tree: improves explosive damage and abilities with weaponry, especially Rocket Launchers.
Borderlands 2 redraws the playing field with a new set of character classes that players may select from. The original cast from Borderlands return in supporting roles.
The Borderlands 2 classes are:
- Maya - The Siren, who can Phaselock her enemies in a stasis bubble to help control the field of battle.
- Cataclysm tree: Skills offering a wide range of damage types.
- Harmony tree: Defensive upgrades focusing on character health values. Defensive upgrades based around damage prevention.
- Motion tree: Upgrades to Phaselock for crowd control. Mixture of defensive and offensive abilities.
- Salvador - The Gunzerker, who can unleash a wild barrage of gunfire as he launches into a gun-waving battle frenzy.
- Brawn tree: Focuses on physical toughness.
- Gun Lust tree: Increases weapon stats and grants various abilities.
- Rampage tree: Stat bonuses and abilities tied to simultaneously wielding a gun in each hand.
- Axton - The Commando, who can deploy a Sabre Turret, dramatically increasing the available firepower on the field of battle.
- Guerilla tree: General combat enhancements well suited to being in the thick of the fight.
- Gunpowder tree: Damage enhancements suitable for long range fighting.
- Survival tree: Defensive enhancements.
- Zer0 - The Assassin, who can deploy a holographic decoy and cloak himself entirely from view.
- Bloodshed tree: Skills to upgrade Zer0's close combat effectiveness.
- Cunning tree: A wide array of utilities and damage effects.
- Sniping tree: Weapon enhancements with a particular emphasis on sniper rifles.
Borderlands 2 has been created with the capacity to accommodate additional characters from DLCs:
- Gaige - The Mechromancer, who can summon a powerful battle robot to do the wetwork for her.
- Best Friends Forever tree: Skills designed to enhance longevity.
- Little Big Trouble tree: Elemental damage focused, especially shock.
- Ordered Chaos tree: Skills that focuses on close range damage and restoring health and shields as you kill enemies.
- Krieg - The Psycho, who can go into a bloody rage. He puts his guns away then pulls out his 2-handed Buzz Axe and gains 500% melee damage, with melee kills healing him to full health.
- Bloodlust tree: Skills are focused around kill skills and abilities which increase with Bloodlust stacks, such as increased damage, reload speed, and grenades.
- Mania tree: Focuses on melee attacks, including allowing Krieg to morph into a Mutant Badass Psycho.
- Hellborn tree: Focuses on fire damage and giving perks such as damage resistance to Krieg while he himself is on fire.
Borderlands: The Pre-Sequel
Borderlands: The Pre-Sequel brings four new vault hunters (who are NPCs or significant characters in previous games, with the exception of Aurelia) who work for Handsome Jack and assist in his rise to power, whilst searching for a new vault on Pandora's moon, Elpis.
- Athena: The Gladiator, first seen as an NPC in The Secret Armory of General Knoxx. Uses her Kinetic Aspis shield to block enemy attacks, and can return the damage collected by her shield by throwing it at an enemy.
- Phalanx tree: Focuses on combat support and improves the offensive and defensive capabilities of the Aspis.
- Xiphos tree: A melee-focused tree which augments Athena's melee attacks with the introduction of bleed and bleeding-based skills.
- Ceraunic Storm tree: Heavily dependent on shock and incendiary damage; introduces Maelstrom which increases Elemental Damage the more electric/fire damage she deals, and also unlocks Maelstrom-based buffs.
- Wilhelm: The Enforcer, a mercenary with an addiction to cybernetic enhancements who eventually becomes a boss in Borderlands 2. He can summon two drones to aide him in combat. Wolf will hunt enemies on the field and Saint will hang back to replenish Wilhelm's health and shield.
- Hunter-Killer tree: Mainly improves Wolf's offensive abilities, reduces Action Skill cooldown, and increases Wilhelm's efficiency with elemental weapons.
- Cyber Commando tree: Enhances Wilhelm with cybernetic implants, which grant improved abilities and resistance.
- Dreadnought tree: Boosts Wilhelm's resistance, and improves Saint's supporting capabilities by granting party skills.
- Nisha: The Lawbringer, who eventually becomes Handsome Jack's girlfriend and runs the town of Lynchwood. She can activate "Showdown", which automatically locks onto enemy critical spots and grants her improved gun capabilities in almost every way.
- Law and Order tree: Focuses on Order, which improves survivability while dealing and taking damage, and grants melee-oriented buffs.
- Fan the Hammer tree: Improves the ability of low magazine size non-elemental pistols, and grants buffs to Showdown.
- The Riflewoman tree: Grants multiple gun enhancements, with later skills granting western-trope abilities such as trickshots and causing enemies to explode after they are hit during showdown.
- Claptrap: The Fyrestone Claptrap, reprogrammed by Jack during the events of Pre-Sequel to be a Vault Hunter known as FR4G-TP. He is loaded with a malware package called VaultHunter.EXE that restores health fully and constantly heals him, and allows Claptrap to assess the situation before choosing a sometimes appropriate subroutine for the task, which can spread its effects to nearby allies.
- Boomtrap tree: Focuses on explosive-based skills, and grants gun bonuses in general.
- I Love You Guys! tree: Team-focused skills that grant more benefits the more players there are in Claptrap's team, in addition to healing support tools.
- Fragmented Fragtrap tree: Introduces Subroutines, which slowly change over time and grant bonuses to a specific gun type, element, or health/shields.
Character DLCs expand the character selected even further:
- Jack: The Doppelganger, initially an intern named Timothy Lawrence who was turned into a body double for Handsome Jack in order to pay off his student loans. He is armed with a hologram projector that lets him summon an endless supply of Digi-Jacks to deal with his enemies (although only two can be on the field at once).
- The Hero of this Story tree: Improves the combat ability of Jack and his clones, and grants skills that focus on free grenades.
- Greater Good tree: Rewards Jack when he allows his Digi-Jacks or friends to get in trouble, and grants several area-of-effect skills for his clones.
- Free Enterprise tree: Focuses on improving gun effectiveness, mainly through gun-swapping and manufacturer gimmicks.
- Aurelia: The Baroness, and the sister of Sir Hammerlock. Her love for hunting game eventually caused her to wind up in the midst of Jack's efforts of saving Elpis. She carries a Frost Diadem Gem that she can toss out to freeze her enemies.
- The Huntress tree: A tree heavily oriented with Sniper Rifles.
- Cold Money tree: A cryo-focused tree which improves the effectiveness of the Frost Diadem and all Cryo damage dealt.
- Contractual Aristocracy tree: Grants benefits through contracts, which improve both Aurelia and another player while it is active.
- Regardless of mentions about weapon preferences, all characters can use any type of weapon throughout the game without penalty. However, certain characters have abilities in their respective skill trees that can augment the use of a certain weapon type, such as Roland's Scattershot, or Zer0's At 0ne with the Gun.
- The main characters (in the core series of games) are often referred to as "Vault Hunters" in the story, due to the their role in the course of events as soldiers of fortune seeking the Vault and its rumoured treasures.
- In the mission Wanted: Dead!, displayed text from each character highlights their individual personality traits. Lilith's cursive script is signed off with a kiss mark and dots her "i"s with hearts, Mordecai uses a hasty scrawl, Roland prints plainly and neatly in capitals, and Brick's writing is a barely legible and childlike scribble.
- Although not an official member of the team, the NPC Michael Mamaril makes mention of himself also being a Vault Hunter before offering a weapon.
- Fiona and Rhys who appear on the Tales from the Borderlands trailer are pointed out by Marcus of not being Vault Hunters despite their intentions of performing something that normally a Vault Hunter would do.
- Prior to invading the abandoned Atlas facility controlled by Bossanova, Zer0 simply shoots his way into the building with virtually no effort and kills everything in his way. When Sasha asks Fiona why they don't just go in the same way, Fiona reminds Sasha they aren't "Vault Hunters". The group then finds a (mostly) non violent way into the building.