Babsgirl- the nickname for the original Batgirl, Barbara Gordon.
Bats - Batman
Batsy! (Yes, he's been called that by some fans too.)
Bat-Hat - The bat-eared Russian fur cap that Batman wears in the ElseworldSuperman: Red Son. Also called the Sexy Bat-Hat, because general consensus is that it's the sexiest damn thing found in comics ever. (It is natural to want to touch a hat so sexy.)
The Goddamned Batman - Batman, especially during his more sociopathic moments. Comes from an actual quote◊ from Frank Miller's crazy run on All-Star Batman & Robin.
Some fans specifically refer to Frank Miller's version as The Goddamned Batman, to differentiate him from the real mainstream version. For similar reasons, All-Star Batman & Robin is commonly referred to as ASSBAR.
The ASBAR Batman can also be "BINO" ("Batman in Name Only")
The nickname has been used when referring to the (mildly) Darker and Edgier Nolan films, particularly TDK- occasionally 'Gosh Darn Batman' in reference to the... ambiguous PG-13 rating. (Mommy? I'm scared.)
'Gosh Darn Batman' has also been used as a parody of the name in an issue of Superman/Batman.
GunBats: Jason Todd's psychopathic gun-wielding Batman.
'Other'? What about Lori Lemaris, Lupé Leocadio, Lana Lang, Lena Luthor, Lionel Luthor, etc., etc...
To the point that one comic llampshaded this with a llama.
"Wondy" is a common nickname for Wonder Woman, "Polly" for Hippolyta and "Temi" for Artemis. The current Wonder Girl, Cassie Sandsmark has a few...unflattering nicknames herself.
"Shamazons" is the common nickname for the spectacularly misconceived Amazons Attack.
"Heinboot" is also the nickname for Wonder Woman's post-Infinite Crisis reboot by Alan Heinberg.
Wonder Woman fans even have nicknames for various costumes."Bathing suit" and "star spangled panties" for the regular costume, "The Screaming Chicken Armor" for her Kingdom Come eagle armor, and "The Christmas Sweater" for Cassie Wonder Girl's current costume.
Preboot - The Legion's original continuity, 1958-1994, 2007-present.
V4 / 5YL / Glorithverse / TMK - "Five Years Later", the fourth volume of the preboot title, a Darker and Edgier continuation following (as the title suggests) a five-year Time Skip; this timeline was created by the time-controlling villain Glorith. The 5YL stories were mostly written by Tom and Mary Bierbaum and drawn by Keith Giffen, usually abbreviated to "TMK".
SW6 - One of the most significant ongoing storylines from 5YL, involving a group of time-paradox duplicates of the early Legion (who went on to star in the Spin-OffLegionnaires until Zero Hour). The term comes from the cryptic labels of the People Jars ("Batch SW6") the duplicates were found in.
Retroboot / Deboot / Johnsboot - The version of the original continuity Legion that appeared starting in 2007's "The Lightning Saga", branching off from the preboot continuity just before 5YL, masterminded by writer Geoff Johns.
Postboot / Archie Legion - The Post-Zero HourContinuity Reboot of the series, 1994-2004. It had a Lighter and Softer, less epic feel to the stories compared to previous runs, and Moy, the Legionnaires artist for the first run of the reboot, contributed a cartoony art style.
The Giant Yellow Space Bug: Parallax, after it was revealed in Sinestro Corps War that instead of "Parallax" being the name of the mass-murdering psychopathic super-villain Hal Jordan became after he lost his marbles over the destruction of his hometown, it was actually the name of the malevolent entity that possessed him, which was...well...a giant yellow space bug.
Also now used as a label for any massive retcon-revelation that completely alters a past event in continuity.
Parallax possessing someone is usually referred to by sticking some form of "-allax" after the possessee's name. Halallax, Kylellax, etc.
Crabface, Crabmask - Kyle Rayner, the only Green Lantern from 1994 to 2004. Because his mask looks like a crab. Kind of. Sort of. If you tilt your head, squint, and have head trauma.
Rage Cat/Rage Kitty - Dex-Starr, the blue "talking"cat that's a member of the Red Lantern corps. The Red Lanterns are powered by their rage and hatred. Scans Daily has dubbed him "Ruffles". Sometimes the names are combined into "Ruffles the Rage Kitty".
Also "Pukecat" (because Red Lanterns puke blood as a weapon).
"Cap" usually refers to Captain Marvel or Captain Atom. In a broader sense, any superhero with "Captain" in his or her name can be called Cap. (Over at Marvel, Cap is Captain America).
Jobberseid - Darkseid, of The DCU. Often used in reference to his more recent incarnations where he loses to almost every superhero on the DC roster, despite supposedly being a threat to the entire universe.
"Couchseid", "Darksofa", "Mr. Couch-Sitter" (among numerous variations), from an infamous scene in Countdown to Final Crisis where the lord of all evil just chills out in Mary Marvel's couch for an issue.
The Three Old Men - Green Lantern (Alan Scott), The Flash (Jay Garrick) and Wildcat (Ted Grant), the three remaining JSA members from its 1940s origins. Occasionally, Hawkman is the fourth old man, but due to the various retcons and reimaginings of his origins, he may not still count as the same 1940s incarnation.
Incidentally, Hawkman is sometimes referred to as "Hawk-Snarl".
"Gay for Justice", the name given to the much-maligned "Justice League Cry for Justice" miniseries that amidst its other terrible decisions made the first word of its subtitle look very much like "gay" due to capitalization and font.
DC Nation posters refers to "Cry for Justice" as "Cry for Good Writing"
Countdown to Final Crisis is so reviled it defies having a nickname. It's name is simply pronounced in a tone of withering disgust, conveyed through the internet with italics, emphatic ellipses, or is preceded by notation such as *seethes* or *grinds teeth* or *groans*
Peej refers to Power Girl, based on the acronym PG. The nickname is frequently, but not always, used by fans who are annoyed that a woman who is at least in her mid-twenties is referred to as "girl."
"The Stick" - A nickname for detractors, commenting on her sudden weight loss in the New 52.
The big blue junk - Dr. Manhattan's... erm... equipment in Watchmen
Downtown Manhattan, Lower Manhattan, the manhattan meatpacking district...
Interestingly, an in-universe Fan Nickname exists for his ability to teleport anyone anywhere, "The Manhattan Transfer".
Before the evil author finally wrote in the names of Snow and Bigby's children in Fables, some of them had fan nicknames. Most common was "Puff" for the seventh, an invisible wind-sprite to the point where there was even a filk about "Puff the Magic Wind Cub." Eventually, his name was revealled to be "Ghost." Apparently, Bigby wants his kiddies names to sound cooler.
Cap - Captain America. Has been canon for awhile, but still one of the most popular nicknames fans use for him.
The Mighty Shield - Carried by Captain America. Never referred to as such in the comics. Often referred to as such on fan discussion boards. Comes from the theme song to a '60s cartoon: "When Captain America throws his mighty shield!"
Shellhead - Affectionate nickname for Iron Man, used by his allies.
Also often referred to as "Tin-Man", though less frequently.
Der Eisenfuhrer - Tony Stark, after leading the effort to throw fellow heroes into the Negative Zone prison camp and becoming head of the Initiative. Usually used derisively by fans as a reference to bad writing (see also: Batdickery).
Also known as "Bureaucrat in Chief" during his 'Director of SHIELD' era
When his armour became sentient and insanely possessive it became known as Tony's "Abusive Boyfriend".
Spidey - Spider-Man, though this one has been canon for a while.
Spidey is even used in Marvel's handbooks, especially the Official Index to Amazing Spider-Man.
Doc Ock - Doctor Octopus; another one that's become ubiquitous both in- and out-of-canon.
Iron Spider/Iron Spidey - The name for the suit worn by Spider-Man during the Civil War. It was designed by Iron Man and even used the same colour scheme. It's since been made official by merchandising and Marvel Ultimate Alliance 2. However, in at least one comic, guys dressed in copies of the suit are referred to as "the Scarlet Spiders" instead. This is fitting, considering that they're clones like the original Scarlet Spider, though not of Spidey himself.
"Douchebag Spidey" or "Jerkass Spidey": post-Brand New Day-Spider-Man, according to some.
"Adjectiveless Spider-Man": The "Spider-Man" title from the 90s, in comparison to the others running alongside it (Amazing, Spectacular, etc.)
SpOck - The Superior Spider-Man, as a combination of Spider-Man and Doc Ock. Spider-Ock is also used.
Claremazon - Quite a few female characters (including but not limited to Storm, Sage, Shadowcat, and Psylocke) when written by Chris Claremont, who had a knack for creating strong super-heroines, and powering up established ones (such as Marvel Girl becoming the Universe-Smashing Phoenix, or Moira MacTaggert now jumping into battle with an assault rifle). Also referred to as "Claremont Woman", to distinguish from the subdued damsels characterized as "Stan Lee girls".
Boobilie/Boobilee- Jubilee of the X-Men. The Decimation event making her lose her superpowers seemingly granted her the Most Common Superpower in exchange by the time she appeared in the latest New Warriors revamp, hence the name.
Wondra Bra has also been coined in relation to her new codename and, erm, assets.
Pooky - Apocalypse. Mostly given the cute nickname due to how often he jobs.
Also "Pocky" and "Ole Pokey Lips", the latter of which was coined by Deadpool (and Apocalypse does have some gigantic blue lips).
Nimbo - Psylocke of the X-Men in her ninja incarnation. Portmanteau of "ninja" and "bimbo", inspired both by her Leotard of Power and her playing the Femme Fatale trying to seduce Cyclops in the '90s. The term has been used for similar characters (e.g. Zealot of the Wild C.A.T.s).
Also The Hellfire Kids or Hellfire Brats or Hellfire Babies. They get a lot of derisive nicknames.
"Adjectiveless X-Men": The "X-Men" title begun by Claremont and Lee, which eventually became Legacy. It was the easiest way to differentiate it from the other titles, and led to other uses, such as Adjectiveless Spider-Man and Adjectiveless Avengers.
"The Pissing Contest" or "The Dick Measuring Contests", and various similar titles are often used to describe Cyclops and Wolverine's recent spat in the main comics and their split. Whenever the two meet and start arguing, usually someone will make a crack about them 'having another Pissing Contest'.
Marvel comics deserves special mention in that it propagated the use of nicknames to refer to many of its own characters with their "next issue" blurbs. For the record, Iron Man is Shellhead, Daredevil is Hornhead, Thor is Goldilocks, Hulk is Greenjeans, Jade Jaws, or the Jade Giant, Spider-Man is Webhead, the Webslinger, and Wallcrawler, etc, etc.
King of Everything - For Norman Osborn when the US Government decided he should be in charge of everything concerning supers.
Rulk (the Red Hulk) was originally a fan nickname but has since gained official status in the books.
Before even being confirmed as a real deal, a group of the most powerful villains in Marvel Universe Including Molecule Man, the Beyonder and Mephisto that appeared at the last page of Dark Avengers #10 were nicknamed The League Of Ultimate Evil And Enchantress.
Shulkie - She-Hulk. Amusingly, the official writer that coined the term later went on a huge rant about people using fan nicknames like "Bats" and "Supes", saying it was disrespectful. This from the guy that nicknamed one "Shulkie".
To be fair, it would hardly be the only example of rampant hypocrisy stemming from one of Byrne's rants against anything and everything he finds wrong with the comic world.
Let's not forget "I've come to enjoy being called Polly," from Hippolyta. At least Jen is a deliberately playful character who doesn't take herself particularly seriously. The Queen of the Amazons, less so.
The Juggernaut, Bitch - The Juggernaut, based on the parody. Some people actually refer to him by this in full.
This one may have since gained semi-official status, as Spider-Man has recently been cited as referring to him in universe as such.
At one point, Joe Quesada threatened to have him officially named "Thone" (i.e., "Thor Clone"). His canon name has since been established as Ragnarok.
As this was an increasingly annoyed Joe Quesada (also nicknamed Joe De Sade), said threat would be for Thone to stand for Thor-One and debut more Thor Clones unless everyone stopped complaining about Civil War..
The Marvel Zombies official, canon reality number is actually 2149, as stated by the official website. Absolutely no idea where Earth 666 has come from.
"Earth 666" is a play on "Earth 616", which is the mainstream Marvel Universe. Sources have been mixed as to why it's "616" but it generally is thought to do with the first publication date of Fantastic Four (In 1961, in the 6 month (June))". Generally, Marvel Universes are labeled by arbitrary numbers, though most have a connection to the publication date of the first comic to to take place in that Universe, though this isn't always the case.
Iävengers - The 'evil' Avengers from the Marvel Cthuluverse as seen in Realm Of Kings.
On a similar note to Darkseid (see DC), The Juggernaut since his Heel-Face Turn has been known as Jobbernaut, though since he got his powers back and it is implied that he will make a Face-Heel Turn, the name may soon be nonapplicable.
And before that, Lady Hawkeye for Kate Bishop, to differentiate her from Clint Barton. Became especially necessary once they both started using the name. Matt Fraction himself refers to her as Lady Hawkeye, as seen in the letters column.
"Barakapool" for the In Name Only version of Deadpool seen in X-Men Origins: Wolverine. Headpool for the zombie version of Deadpool after he had his head chopped off.
Helldad - Hellboy's demon father, who is a demon prince, rather than the devil, in the comics. His name is most likely Azzael, but this is not revealed until many issues after his first appearance.
Phone books - the 2000 ADtrade paperbacks published by Rebellion, which have similar physical dimensions to phone books. Also frequently used to describe the trade paperbacks that Cerebus the Aardvark was reprinted in, even by the actual creator.
Rohmagol - The fan theory that "Rohlan Dyre" in the Knights of the Old Republic comics, starting with issue 14, is actually Demagol in his armor, posing as him.
Tower Head Girl - the so far nameless super who has a 5-foot cylinder of greebled metal growing out of her head in Empowered.
The Moose - the monster in the wall in Johnny the Homicidal Maniac. So called because one character says it sounds like either rats in the walls or possibly a moose, and later there's a note saying 'definately not a moose'.
In Brazil, Michonne from The Walking Dead is often called Machona/Machonna (something like "manly girl").
The King - Not Elvis, but Jack Kirby, comic book writer and artist who co-created 90% of the Silver AgeMarvel Universe with Stan "The Man" Lee, and created Darkseid and the New Gods, along with many other characters and concepts, over in The DCU. Owing to this, many other fan nicknames derive from his name.
Stan Lee claims to have coined both the "King" nickname as well as "Jolly Jack" for Kirby. He indeed coined many such nicknames, usually of the rhyming or alliterative type to make Marvel's employees more well-known and "accessible" to the fans, and more than a few were taken up by the fans, including "Smilin' Stan" Lee, "Sturdy Steve" Ditko (a nickname Ditko himself disliked), Gene "the Dean" Colan, and "Jazzy Johnny" Romita (Sr., aka John "Ring-a-Ding" Romita).
Alan Moore's Top 10 referenced Kirby's style several times, as well as referring to a version of him existing within Top 10 continuity known as "King", who painted murals of Science Heroes in a similar manner to Norman Rockwell painting murals of people.
Kirby hats - Jack Kirby designed a number of characters with weird helmets. Galactus is a good example.
Kirby tech - Machinery that is covered with a mess of buttons, wires, tubes, and other visually interesting details.
Kirby Dots - Stylistic manner of depicting energy.
Also known as "Kirby Krackle".
D'n'A/DnA - Dan Abnett and Andy Lanning, writing partners for Marvel's cosmic line in the 2000s and (for at least some period time) The Authority.
Joephisto - Marvel Comics editor-in-chief Joe Quesada, thanks to the spectacularly misconceived One More Day storyline in Amazing Spider-Man, which retconned Spider-Man's marriage by having him make a deal with the Marvel Universe's resident Devil, Mephisto. J. Michael Straczynski, who was writing Amazing at the time, asked to have his name removed, but was eventually talked out of it. Quesada was completely for this change, despite earlier promising not to mess with Spider-Man's history via a "magic retcon".
Other fan nicknames include "Joe Quesadilla", "Big Joey Cheese", and "That Bastard".