People using the internet will rarely go by their given name. Writers seem to have some very specific ideas of how this works. The Cracker and Playful Hacker will use an alias as a pseudonym for all their hacker-y deeds (in extreme cases they'll only go by that name). They tend towards single words or two word phrases (preferably cool sounding).
Expect generic references to popular characters and streams of numbers and letters appended to the end, or replacing some of the characters. It will almost certainly involve a pun on the user's given name if they're an important character. If an aforementioned "hacker" uses one of these it's generally to show that they're rather pathetic. Either way, expect usernames to be full of Xtreme Kool Letterz or be Names to Run Away from Really Fast. Their online alias could also be a Lazy Alias if poorly put together.
In more recent works, since Technology Marches On, there's a fair chance there will be a more "normal" screen name for a character with an email or IM address.
No one will go by the same or a similar handle and the main characters will never have any trouble getting a username derived from their real name no matter how common it is (unless it's being Played for Laughs), since It's a Small Net After All.note
Computers often have cool names too; see Names Given to Computers.
- Gundam Build Divers: All the main cast have GBN usernames derived from their real names - Yukio "Yukki" Hikada, Momoka "Momo" Yashiro, Koichi "KO-1" Nanasenote , Aya "Ayame" Fujisawa, and... Riku "Riku" Mikami (written in English rather than kanji).
- Yuusha Gojo Kumiai Kouryuugata Keijiban (AKA, Hero Union BBS) is framed as a series of threads on an interdimensional message board, so every character is primarily known by a handle. New users are called "Hero" by default, but they soon differentiate themselves by profession or world of origin, like recurring characters Student, Sage, Freeter, and Princess Shrine Maiden. A few even have new handles forced on them, like the college student who gets dubbed Magical Girl despite being mortified by her patissier-themed costume.
- December 3, 1999: Jon goes on a chat room under the name "Stephano", describing himself as "very rich and macho." According to Garfield, "nobody can empty a chat room like Stephano."
- September 24, 2008: A comic revolves around Garfield using a cat chat room. His username is Garf1, and there are unidentified users named Whiskers232 and Pussnboots113.
- In The Matrix the rebels seems to adopt their handles as their names. Amazingly enough, their aliases are cool and mysterious... presumably because having a character named "Yoda324" would have ruined the tone of the movie.
- Hackers, oddly enough, averts this partly; most people use two word phrases, like Acid Burn or Crash Override.
- Kevin Smith appeared in Live Free or Die Hard as a Playful Hacker who considered his hacking Serious Business and went by the Xtreme Kool Letterz name of W4RL0CK or some such thing.
- The Transformers live-action movie has Decepticon Barricade grill the protagonist over his alias:
"Are you LadiesMan217?"
- In Jay and Silent Bob Strike Back, the title characters are badmouthed by a bunch of anonymous internet loudmouths, all of whom are using an alias online. The most obnoxious of whom was named after an actual Troll on Kevin Smith's forums. (Perhaps a troll's CMOA.)
- In Toy Story 3, someone by the name of Velocistar237 AIMs Trixie, temporarily interrupting Woody's attempts to use Bonnie's computer.
- Thor trash-talks Korg's rival in Fortnite in Avengers: Endgame who has the online alias of NoobMaster69.
- In Tad Williams' Otherland novels, one of the main characters goes by "T4b". Presumably pronounced "Tab".
- Animorphs mostly features the "modern" idea of names: YeerKiller9, Gump8293, etc. But it also has some more hacker-like ones, like "Govikes" and "YrkH8er".
- Lisbeth Salander from The Millennium Trilogy goes by the hacker name "Wasp," which becomes a plot point as Mikael is able to track her down using it. She initially had a tattoo of one on her neck, but The Girl with the Wasp Tattoo doesn't have the same ring to it.
- Snow Crash has Da5id and, of course, Hiro Protagonist. They go by that in meat-space, too.
- All the hackers in Vernor Vinge's novella "True Names" use these to keep their identities secret from the cops ("The Great Enemy") as well as each other. Mr. Slippery, Erythrina, Wiley J. Bastard, The Slimy Limey, DON.MAC, and The Mailman are just some of the characters known mainly or exclusively by their aliases.
- In The Romulan Way by Diane Duane, it's explained that the Romulans' secret fourth names originated as online handles on the Vulcan version of the Internet.
- In Sword Art Online, characters tend to get referred to more often by their MMORPG characters' names than their real ones, both in-series and out. A few characters' aliases are derived from their real names; for example, Kazuto Kirigaya goes by "Kirito" and Shino Asada goes by "Sinon". Asuna using her real name in Aincrad is cited by some characters as proof that she's a newbie (she adopts the aliases "Titania" and "Erika" in later games).
- ½ Prince has most of the characters refer to each other by their Second Life character's name once they meet offline, because it's simply easier for them to recognize each other this way.
- Log Horizon: Most characters also use usernames instead of their real names, when even some of them have friends who've learned their real names. At least three characters are known to have derived their username from their real name - Kei "Shiroe" Shirogane, Marie "Maryelle" Sakamoto, and... Naotsugu "Naotsugu" Hasegawa.
- Infinite Dendrogram has a few cases of "clever" usernames backfiring on their users:
- Reiji and Shuichi Mukudori named their MMO characters "Ray Starling" and "Shu Starling", and are fully open about being brothers. This is such a blatant case of This Is My Name on Foreign that Reiji accidentally doxes both himself and his brother the first time he meets another Dendrogram player in real life.
- "Marie Adler" roleplays as a journalist, styling herself after an obscure manga character with the same name. In real life she's the author of said manga, trying to better immerse herself in the character's head. She is actually far stronger than she appears, being the legendary hitman PKer known as the Superior Killer. Which everyone familiar with her manga has figured out already, because the manga Marie is a hitman disguised as a journalist.
- In one episode of the 11th season of Law & Order: Special Victims Unit there is a guy who goes by "Master Bater".
- In an episode of My Family Ben is getting advice from a forum. A joke is made about the wisdom in getting advice from someone going by the name "Yoda2".
- In one episode of The Drew Carey Show, Drew, as BeerStud2, has cybersex with a woman calling herself HoneyBee28, who turns out to be his Sitcom Archnemesis Mimi.
- In Sex and the City, Stanford uses the screen name Rick9Plus on a gay hook-up site, and ends up having cybersex with someone calling himself BigTool4U. More mundanely, when Carrie sets up her first AOL account, she chooses the username "shoegal".
- In one episode of Elementary, Sherlock discovered a potential suspect who had been online with the victim, but was confused as to why a male suspect would call himself "Lego Lass". When they met him, he explained he was "Legolas5".
- Deckers in Shadowrun used mysterious and cool names if they were established and competent and ridiculous and common aliases if they were newbies. The first type were usually used as runner aliases as well.
- Several are revealed after completing Lair of the Shadow Broker in Mass Effect 2. Miranda Lawson fittingly goes by LawBringerSR2. Jack uses Jck_60734, jkz0-19510, and, (for a submission to a professional poetry forum), Jaqueline Nought. Legion humorously goes by Infiltrait0rN7 for his MMO gamer profile.
- Snake Fist in F.E.A.R 2: Project Origin, AKA Terry Halford. His 90's style handle is in-keeping with his status as Comic Relief who serves as a slightly awkward Mister Exposition and a Voice with an Internet Connection Until his untimely death.
- In The Sims 3, there is a Sim in Sunset Valley who goes only by his online alias, "Cycl0n3 Sw0rd".
- Many people in Deus Ex: Human Revolution have online aliases. The most prominent is probably Francis Pritchard's "Nucl3arsnake".
- An interesting case in Uplink. The online handle that you choose for yourself at the beginning is also used as your legal name when you hack the Social Security or law enforcement databases. That's right, your Social Security Number belongs to a person legally named L33tH4x0r. Everybody else just goes by their normal name, including the world's top hackers.
- Matt Miller, the leader of the Deckers gang in Saints Row: The Third, uses R4gn4r0k as his alias, though that only comes up in supplemental material.
- Marcus Halloway in Watch_Dogs 2 goes by "Retr0" in online hacking circles, even before he joined DedSec. Josh, another DedSec member, uses "Hawt Sauce" as his handle.
- In Life Is Strange, Max goes by "Noir Angel". A Shout-Out to another heroine named Max with strange powers.
- All the main characters in SC2VN use their online gaming aliases. Their real names are never revealed.
- In Penny Arcade:
- Ben from Loserz is "zombiejuiceYUM". Jodie is "p0rnstar6912". See this strip.
- In The Noob, a little girl gets perma-banned by the KKK-like moderator without so much as a word of explanation, when he mistakes her character for the protagonist's, due to them having similar (but not identical) appearance and name.
- Chat nicknames used in General Protection Fault: Gort (Nick), Pookel (Ki), B0R0M1R (Yoshi).
- The Guild, being a show on the web about gamers, definitely uses this. We sort of know the real names of the characters - all but Tink - but they rarely get used in favour of their gamer handles.
- All of the main protagonists (yes, all 16 of them) of Homestuck have "chumhandles" that they use in their in-universe version of Instant Messager. All of them reflect the user's interests, personality or foreshadows their role in the series. They also follow a specific pattern of Theme Naming.
- Notably averted by the White Text Guy, who communicates to the protagonists through their IM clients, but doesn't have a chumhandle. Or even a computer.
- Also, a good part of the fandom has adopted online aliases following the convention of two words in Lower CamelCase.
- And then parodied when we see the usernames of some GameFAQs posters, such as "ChaosDemon" and "winnie the poop 2".
- Library Of The Damned has a Command Staff Chat for the Riffleet. So far, we only know that agig (The Character) is agigtheadmiral, thanks to a gag involving Xtreme Kool Letterz.
- Everyone in Noob, that happens almost entirely in a MMORPG. Only the (real) names of the main characters, some people from their faction, the game's creator, the recurring Game Master and the recurring hacker are known.
- A Something Awful cyberpunk parody included, among others, a character known as "Haz Cheezburger."
- In the Shared Universe of Sunstone and Blood Stain, the main characters of both comics interact with each other through the in-universe MMORPG. We see in-game usernames in a supplemental comic, and we see a subversion for this trope; the usernames are clear references to their real names. Ally's and Dr. Stein's usernames are puns on their names ("allycat", "bloodstein"), while Lisa's and Elliot's are goofy but still clear ("liiiiiiiiisa", "ellyoldcoot").
- Sword Art Online Abridged uses most of the names from its source material, but throws in some twists. Agil goes by "Tiffany" in this treatment for as yet unexplained reasons, even though he's fully aware it's a woman's name. Klein got trapped in SAO under his test character profile, BallsDeep69, so soon his guildmates think "My name is Klein!" is how he says hello. And Kazuto gains enough notoriety in Aincrad as Kirito to have his preferred handle already taken when he tries out Alfheim Online - after hours spent going through permutations such as Kirito1, Kirito2, or Kiritwo, he ends up logging in under xVx_K1r1t0_xVx_KillMe; Kazuto shortens it when talking with Leafa, aka Suguha, who realizes who he is as a result and expresses squick-induced outrage back in realspace.
- Arthur: In "Buster the Myth Maker", Brain posts false information online under the name "Deep Float". The name comes from the ice cream shop his family owns.
- In Phineas and Ferb, Doofenshmirtz is on a dating site, and goes by the name of StrudelCutie4427. Unfortunately, his date thinks Perry is much cuter.
- On South Park, Stan's World of Warcraft character was actually "Loves2Spooge". Leading to the line:
"I heard... iLoveSpooge2 lives here?"
- In one Venture Brothers episode, The Monarch's date (whom he found online) for a double-date with Phantom Limb and Dr. Girlfriend thought "The Monarch" was one of these.