Not much is known about Zer0, including his real name. He is called Zer0, simply because a hologram of the number "0" appears from his forehead whenever he assassinates a target. The holo-emitter can display other symbols and images, including a smiley face, from time to time. Zer0's regular melee attack uses his sword, which is not a separate piece of equipment, but it can be enhanced by various skills.
ACTION SKILL: DECEPTION
Zer0's unique ability is called Deception, which renders him invisible to enemies, while creating a decoy of himself. While he is cloaked, he can go around the battlefield and deal critical strikes to enemies, who have locations on their body highlighted in blue to signify their weak spots. The longer Zer0 is cloaked, the more damage he is able to dish out, but he is not completely invincible while using Deception, as he can take damage from grenades, explosives and other forms of splash damage. Also, the longer he is cloaked, the longer the cooldown for the ability.
Up to 650% Melee damage, Up to 200% Gun damage, Up to 250% Gun critical hit damage
SNIPING Skill Tree
This Skill Tree focuses on ranged combat, especially with Sniper Rifles.
| NAME | TIER | LVLS | DESCRIPTION |
| Headsh0t | 1 | 5 | Increases Critical Hit Damage (4% per level). |
| 0ptics | 1 | 5 | Increases your Zoom (3% per level) with all gun types. Also, your Aim (12% per level) is not disrupted as much when taking damage. |
| Killer | 2 | 5 | Kill Skill. Killing an enemy gives you bonus Critical Hit Damage (10% per level) and Reload Speed (15% per level) for a few seconds. |
| Precisi0n | 2 | 5 | Improves your Accuracy (5% per level) with all gun types. |
| 0ne Sh0t 0ne Kill | 3 | 5 | The first shot fired from a fully loaded magazine causes Bonus Damage (12% per level). |
| B0re | 3 | 1 | Your shots pierce through enemies. If your shots hit an enemy after piercing an enemy, it causes massive Bonus Damage (additional 100% damage). B0re does not work with rockets and some special projectiles. Also, while Deception is active, your visor will highlight enemy crit locations. |
| Vel0city | 3 | 5 | Increases Bullet Speed (20% per level), Damage (2% per level), and Critical Hit Damage (3% per level) with all guns. |
| Kill C0nfirmed | 4 | 5 | Aiming Down the Sights with your gun grants you a bonus to Critical Hit Damage (up to 8% per level). The longer you aim down the sights, the greater the bonus. |
| At 0ne with the Gun | 5 | 5 | Greatly improves your Accuracy (25% per level) with Sniper Rifles when shooting from the hip. Also increases your Reload Speed (10% per level) and Magazine Size (+1 per level) with Sniper Rifles. |
| Critical Ascensi0n | 6 | 1 | Scoring a Critical Hit with a Sniper Rifle increases your Damage (5% per stack) and Critical Hit Damage (6% per stack) with Sniper Rifles. This effect can stack up to 999 times. Stacks slowly decay if you haven't scored a critical hit in awhile. |
CUNNING Skill Tree
This Skill Tree seems to focus on improving Deception and on improving both his ranged and melee combat.
| NAME | TIER | LVLS | DESCRIPTION |
| Fast Hands | 1 | 5 | Increases your Reload Speed (5% per level) and Weapon Swap Speed (10% per level). |
| C0unter Strike | 1 | 5 | After getting hit, your next Melee Attack has a chance to deal massive Melee Damage (50% per level). |
| Fearless | 2 | 5 | While your Shield is depleted you gain increased Gun Damage (3% per level) and Fire Rate (5% per level). |
| Ambush | 2 | 5 | Increases Damage when attacking from behind (4% per level) or when attacking an enemy who is targeting someone other than you. |
| Rising Sh0t | 3 | 5 | Each successful Ranged (2% per Gun Damage stack) or Melee Attack (1.8% per Melee Damage stack) gives you a Damage bonus for a short time. This bonus can stack up to 5 times. Faster weapons can gain stacks more quickly, but slower weapons retain stacks for a longer period of time. |
| Death Mark | 3 | 1 | Dealing Melee Damage marks the target for a short duration (8 seconds). Marked targets take additional Damage (20% additional damage) from all sources. Also, it's not an easy thing to live with. |
| Unf0rseen | 3 | 5 | Your holographic decoy explodes when you become visible again, causing Shock Damage (1 rank per level) to nearby enemies. |
| Innervate | 4 | 5 | While Deception is active you gain increased Gun Damage (2% per level), Health Regeneration (0.8% of health per level), and Movement Speed (7% per level). |
| Tw0 Fang | 5 | 5 | Every time you fire a gun you have a chance to fire two shots (6% chance per level). |
| Death Bl0ss0m | 6 | 5 | Action Skill Augment. Throw a handful of kunai while Deception is active. Each kunai will explode with a random elemental type. Kunai do not benefit from the Deception damage bonuses, but throwing kunai does not end Deception and can apply Death Mark. May throw kunai 5 times per cooldown. |
BLOODSHED Skill Tree
This Skill Tree is focused more on melee combat.
| NAME | TIER | LVLS | DESCRIPTION |
| Killing Bl0w | 1 | 5 | Massively increases Melee Damage (100% per level) against enemies with low health. |
| Ir0n Hand | 1 | 5 | Increases your Melee Damage (3% per level) and your Maximum Health (3% per level). |
| Grim | 2 | 5 | Kill Skill. Killing an enemy causes your Shields to quickly regenerate (0.7% of your shield per second) and increases your Action Skill Cooldown Rate (1.5% per level) for a few seconds. |
| Be Like Water | 2 | 5 | Shooting an enemy improves the Melee Damage (6% per level) of your next Melee Attack. Melee Attacks improve the Shooting Damage (4% per level) of your next shot. |
| F0ll0wthr0ugh | 3 | 5 | Kill Skill. Killing an enemy increases your Movement Speed (8% per level), Melee Damage (8% per level), and Gun Damage (6% per level) for a few seconds. |
| Execute | 3 | 1 | Melee Override Skill. While Deception is active and a target is under your crosshairs, dash forward a short distance (3 meters) and perform a Special Melee Attack, dealing massive damage. |
| Backstab | 3 | 5 | Your Melee Attacks deal Bonus Melee Damage (8% per level) when hitting an enemy in the back. |
| Resurgence | 4 | 5 | Killing an enemy with a Melee Attack restores Health (up to 4% per level). The lower your health, the more health you receive. |
| Like the Wind | 5 | 5 | While moving you gain increased Melee Damage (3% per level) and Gun Damage (3% per level). |
| Many Must Fall | 6 | 1 | Killing an enemy with a Melee Attack while Deception is active causes you to deploy another holographic decoy, re-stealth, and add time to Deception's duration. This can be done multiple times in succession. |
