Zer0 is the playable Assassin class character in Borderlands 2.
Zer0 was revealed on February 21, 2012, in the Borderlands 2 Launch Date Trailer. His nickname comes from the "0" hologram sometimes displayed over his faceplate when he dispatches a target. Other emotes and text appear on his faceplate - and on enemies, using the B0re skill - during different actions. Most of Zer0's phrases are spoken in haiku.
Zer0 is an assassin for hire. According to his wanted poster and his personal ECHO recordings, he performs both political assassinations and common hits. Following a particularly unsatisfying assassination where the target fails to fight back, despite being encouraged by Zer0 to do so, the assassin starts to look for a more challenging environment. He travels to Pandora after hearing of the Vault from a bartender, deeming the hunt as worthy of his skills.
As his face and body are completely covered by his suit, a certain amount of mystery surrounds Zer0's true appearance. In an ECHO recording, Angel remarks that she's not even sure if Zer0 is human; both in-game and promotional material show that he has only four digits on each hand. His origins and real name are also unknown, leaving the character shrouded in mystery.
As revealed in the "Ask Dr. Tannis" Section of the Pandoran Gazette, included as a scrap of paper in the Diamond Plate Loot chest, Zer0 is not his true name. The remaining piece of scrap containing the name and gender of Zer0 were not included, but the part that does remain suggests that Patricia Tannis is aware of Zer0's origins.
Tales from the Borderlands
Following a mission given by Moxxi, Zer0 chases after the bandit lord Bossanova, in search of a Gortys core. They crash into the World of Curiosities, where Rhys and Vaughn are in the process of dealing with August for a Vault Key. Bossanova runs off with Rhys' money, leaving Zer0 to deal with several psychos. Later, Zer0 tracks Bossanova to his hideout, an abandoned Atlas warehouse, and makes his way inside. He later saves Rhys and Sasha from a skag, and takes a lift with them to the center area, where Bossanova is hosting a death race event. Upon spotting Zer0, Bossanova issues a $20,000 reward to anyone who can kill him. Zer0 engages in combat with Bossanova and his bandits, and eventually emerges victorious. He then reports the situation back to Moxxi, while commenting on not having found the Gortys core. Unbeknownst to him, the core was hidden below him, and is later found by Rhys and Fiona.
If the player identifies Fiona as a Vault Hunter back in Episode 3, Zer0 will be available as a team member in the fight against The Traveler. His attack against The Traveler begins with a form of Decepti0n, followed by teleportation blocks and quick blows.
Action Skill: Decepti0n
"Decepti0n" grants Zer0 the ability to deploy a holographic decoy of himself and enter an invisible "stealth mode." While cloaked, he can maneuver about the battlefield dealing amplified damage on his next attack. The longer Zer0 stays cloaked, the more damage he can inflict to enemies; however, the shorter Zer0 stays cloaked, the sooner he is able to use the skill again. Zer0 does not enter a separate dimension like Lilith when she Phasewalks, and can still take damage from all sources while cloaked.
Decepti0n has a base cooldown of 15 seconds and gives up to +650% Melee Damage or +200% Gun Damage and +250% Gun Critical Hit Damage.
Zer0 has three Skill trees:
- Main article: Class Mod (Borderlands 2)#Zer0
Zer0's basic melee attack uses his sword. The sword cannot be equipped but its effectiveness in combat can be enhanced. It consists of a physical hilt with a blade that digistructs when pulled from its sheath.
Zer0 often displays holographs from his faceplate, revealing his emotions through this. These include:
- :) - a smiley face emoticon, displayed randomly.
- 0 - a large number zero originally giving Zer0 his nickname. It is displayed after an enemy is killed with a melee attack.
- :D - a smiley face emoticon, displayed when constructing and/or entering a vehicle at the Catch-A-Ride station.
- WTF BRO - an acronym for "What The Fuck, Bro," displayed after crashing a vehicle into something.
- <3 - a heart emoticon, displayed while reviving a friendly player.
- FML - an acronym for "For My Loss" or "Fuck My Life," displayed after being crippled.
- ? - a question mark, displayed when pending actions (such as switching seats with a player in a vehicle) or when viewing the map.
- ! - an exclamation mark, displayed when seeing a downed friendly player.
- $ - a dollar sign, displayed when completing a mission.
- && - twin ampersands, displayed when inspecting items in the menu.
- 勝 - a kanji character meaning "victory", displayed when receiving items by either picking them up or via trading.
- ... - an ellipsis, displayed when either inspecting menu items, after killing an enemy, or while reloading a weapon.
- :l - a straight face emoticon, displayed when standing idle.
- ZZZ - three Zs, a common emote for "sleeping," displayed when standing idle.
- :( - a sad face emoticon, displayed when standing idle.
- B0R3D - the word "BORED" written in leet speak, displayed when standing idle.
- 嘆く - a kanji character meaning "sigh," displayed when standing idle.
- OWND - an abbreviation for "owned," displayed after killing an enemy with a critical hit.
- 止 - a kanji character meaning "stop" displayed when trying to fast-travel while a co-op partner has a menu open.
During Decepti0n, with the B0re Skill active, various other Emotes can been seen on the Enemies weak points.
- 00110000 - the binary ASCII code (48) for the digit 0.
- :(_8(1) - an emoticon looking like Homer Simpson from the TV-show The Simpsons.
- >_< - a frustrated person emoticon.
- :-P - a person sticking their tongue out as an emoticon.
- :-D - another smiley face emoticon.
- >:-] - an evil face emoticon.
- [O][O] - two wide eyes as an emoticon.
- [.][.] - a female breasts emoticon.
- ^5 - an emoticon symbolizing a "high five."
- D13 - the word "DIE" written in leet speak.
- K1LL - the word "KILL" written in leet speak.
- 1337 - the word "LEET" written in leet speak, which can also mean "ELITE."
- PA1N -the word "PAIN" written in leet speak.
- W34K - the word "WEAK" written in leet speak.
- 3MTA3 - the words "EAT ME" written backward and in leet speak, which was a saying made famous by Beastie Boys, a hip-hop band.
- 4SS4SS1N - the word "ASSASSIN" written in leet speak.
- <-SHOOT - an arrow and the word "SHOOT," telling one where to shoot.
- WTF - an acronym for "What The Fuck."
- OMG - an acronym for "Oh, My God."
- LOL - an acronym for "Laugh Out Loud."
- GTFO - an acronym for "Get The Fuck Out."
- \M/ - The "sign of the horns."
- \0/ - a person with their arms in the air as an emoticon.
- !!! - three exclamation points.
- 42 - the "Answer to the Ultimate Question of Life, the Universe, and Everything."
- 666 - the "number of the Beast."
- 31415 - the first five numbers of Pi.
- 8675309 - a phone number, referencing the famous song "867-5309/Jenny", performed by artist Tommy Tutone.
- 8===D - the number 8, three equal signs and the letter D, a common text representation of male genitalia.
- Gearbox concept designer, Scott Kester, credits Zer0's inspiration to "loner characters" like Snake Eyes from G.I. Joe and Gray Fox from the Metal Gear video game series. 
- Most of Zer0's dialogue is spoken in haiku, which is noted once by Handsome Jack in an ECHO recorder.
- Zer0's version of the "Slayer of Terramorphous" class mod was once bugged, providing a bonus to one of another playable character's, Salvador, the Gunzerker class, skills. It has since been fixed in a patch.
- When using the Handsome Jack Voice Modulator, Zer0 will become far less talkative. Many of his lines are replaced with lines that are cut short as though Zer0 was about to say something, heard his own voice, and decided against it.
- Zer0's wanted poster has the code 000 000 000 HSP, the joke being that the entire numerical code is just 0s, as part of a running gag Zer0 has with the respective number, along with other jokes in other areas.
- The line, "This is the story / All about how my life got / Flipped, turned upside-down." from killing an enemy by running them over is a reference to the Fresh Prince of Bel-Air's intro song.
- Zer0's line when entering Decepti0n, "How hilarious / You just set off my trap card / Your death approaches." is a reference to Yu-Gi-Oh, where a trap card would be used in response to another player's actions.
- In Mad Moxxi and the Wedding Day Massacre the reward head for Zer0 shows a robotic eye in his shattered helmet. A promotional description stated "it should be said that his new head is named 'N0t C4n0n' for a reason," keeping Zer0's true race a mystery.
- Zer0 speaks in a completely different voice in Episode 5 of Tales from the Borderlands, using a less husky, more formal-sounding voice. This new voice has been widely criticized for being a rather unfitting change.
- Lost ECHO recordings 3 and 4, Sawtooth Cauldron