#1: The parent fatality rate in role plays is likely high enough to cause systemic population problems.

#2: Origin stories are either boring or horrifyingly tragic. There's no such thing as a somewhat depressing life.

#3: Speaking of which, when sorrow occurs, expect it to be a catastrophic internally based event that is all consuming of a character's other traits.

#4: "History" will be used interchangeable with "personality". Whether you like it or not.

#5: "Personality" will be mistaken for emotional states, whether you like that or not.

#6: Characters who suddenly gain competency or even mastery over a skill set will reference a point in their history that was nowhere listed in their history.

#7: A sigh must take several seconds of concentrated detail to get just the right tone to indicate the character's suspected irritation. Much like the reader's own irritation.

#8: Characters magically become competent at the age of sixteen. Prior to that it might be unrealistic.

#9: If the parents are still alive, chances are they have extreme issues with the character, taught them everything they knew, or are so completely distant and removed from the character's life, may as well be dead. (Tempest)

#10: All characters are adventurers. The ones that aren't are usually terrible written.

#11: Characters who claim a trait often don't have that trait. Like a wise character is not wise, a charismatic character is not charismatic, and so on.
Addendum: Unless they actually do, in which case, they have so much of that particular trait that they would be clinically dead in the real world. Like enough strength to blow open a steel door. With their face.

#12: Everyone comes from a backwards shittown that nobody has ever heard of. Ever. (Zed)
Addendum: Or they're a long lost uberpowerful chosen one/member of royalty/etc. (Drago)

#13: Everyone is clean, even in settings where this doesn't make any sense.

#14: Also no such thing as diseases, leave alone STD's or STI's. I mean, who the hell could get AIDS in an environment with no birth control anyway?

#15: While on the topic, there's no such thing as an unwanted pregnancy either.

#16: They are from a evil race but are pure hearted as all fuck. (Hellis.)

#17: Speaking of evil, there's no such thing as only kinda selfishly dickish. If you're evil, you kill babies and rape women and destroy homesteads. Stole something once? YOU ARE EVIL. KILL! KILL! KILL!

#18: Morality is typically portrayed from a pro-western/modern world view, even in time periods where this would be completely inane, or universes where this mindset would be completely incomprehensible. Such as Warhammer 40K.

#19: The D&D alignment wheel will also be used as a morality compass to be strictly adhered to, even in situations where this makes no sense.

#20: Racial stereotypes are abundant, even in stories about how racism and racial profiling is wrong, such as drunken dwarves who are excellent smiths, greedy beyond reason humans, evil or hounourable orcs (sometimes both), egotistical elves, and so on.

#21: So are gender-based ones. Staff chicks are still a thing. Efforts to combat this usually take it to an extreme and apply the wrong principle, like putting a woman in power armour and having her reject all feminine qualities for masculine ones: This isn't fixing the problem, this is slapping a pair of tits on a male fantasy. Good job.

#22: The adventuring party requires an obligatory female. (Esper.)

#23: Women shall never be ugly.

#24: ...Or fat.

#25: Characters are either completely incapable of being serious or so grim dark as to have had their capacity for laughter or smiling surgically removed. (Thanks Drago.)

#26: No one ever has a pre-existing handicap unless: 1) they have a mental illness pertaining to their views on reality or general stability... 2) they lost an eye 3) they lost a limb AND it was replaced with a better one. (Tempest)

#27: Speaking of insanity: There is no such thing as a mild disorder. It has to be all consuming of a character's personality just like sorrow is. Unless it's depression. Then it is sorrow. Endless sorrow. For no reason.

#28: Insanity will also be used as a scapegoat for random, destructive behaviour, even if it wouldn't fit the profile of the disorder...

#29: ...And atop all of this, the mentally unstable are usually portrayed as incompetent at best, or inhumane monsters at worst.

#30: If there is male and female duo. The female is usually the magic user. If they are both magic users she is usually the healer. (Esper)

#31: Love is often treated as being the most sacred power in the universe, despite it simply being another facet of a healthy person's behaviour towards other people.

#32: Love is all consuming and overriding of a character's more logical or sensible nature: To be incapable of thinking of other things is unhealthy at best...

#33: A romance arc is usually wrapped up within a day in the universe. Maybe a week at the most.

#34: No matter how inexperienced, all sex is to be described as being perfect. Always.

#35: Half-bloods will never have any genetically related issues. A half-elf and half-human for example is always without a single potential biological problem as the result of two different species going at it.

#36: Children are either hellspawn or little angels. There is no middle ground on this.

#37: Most role plays will never actually feature children. New characters simply pop out of holes in the ground. This is especially poignant for a fantasy RP where players walk through towns of adults... And only adults.

#38: All legal ages now are the same as in the past or in the future. After all, medieval peasants totally waited until they were eighteen to get married and have kids. Totally. Mmhmm.

#39: Mages are either miracle genius children or bumbling old men. Technicians usually also follow under this trait.

#40: Characters always seem to know the right answers for any problems. There is never any problem they don't know how to resolve inherently, or god forbid incorrectly.

#41: A character's religion is usually shared auspiciously with their author.

#42: Anime pictures and oriental names or weapons being used on characters that are not in any way, shape, or form, oriental.

#43: There is no such thing as a power curve. Characters either never grow in strength or grow whenever they feel it convenient.

#44: Loners nearly always have a tragic past and nearly always gravitate towards a romantic relationship with the nearest person of the opposite (or sometimes same) gender whom pays them any sympathies.

#45: Roles often determine personality traits: Warriors are aggressive and stubborn, mages are intellectuals, thieves are cunning, rogues are wily, technicians are ingenuitive, godmoders are mary sues...

#46: Mary Sues will always be demonized as being the utmost of all evils and being flawless, despite the fact that their main characteristic of believing they're own flawlessness is narcissistic and inherently flawed...

#47: If a character has banged a hot lady/man, she or he will bang more then 1 within the near future. (Hellis)

#48: FxF, MxM, FxM, or otherwise sexually-based determinations for characters to have in a future role play increase the chances of explicit sexual content to occur in the IC. If anything along the lines of submissives and dominants are mentioned, your best option is to run away before you get banned.

#49: Speaking of retreat, this will never happen. Nobody runs away from a fight unless the entire point of the role play is to constantly run away.

#50: Most often characters in danger aren't. Damn you plot armour! Damn you to hell!

#51: The more war-based experience your character has, the more likely they will die horrible as an example to all the others about how horrible the situation has become.

#52: Characters never suffer from crippling levels of panic or fear. They could be a peasant wielding a pick axe or a fresh recruit for a war, but by god if they aren't some of the damned bravest red shirts ever to grace the field.

#53: ...Characters with names have a much greater chance of survival.

#54: ... Unless their name is Jimmy.

#55: Names often reflect the nature of a character. The softer the name, the kinder they are. The more serpentine or coarse the name, the rougher they are. After all, when was the last time Jimmy bullied Butch?

#56: There's no such thing as characters over 40 unless their only remarkable trait is to be that "one old guy" who constantly remarks about "being too old for this shit".

#57: If a character has a top secret code, the big bads will for some reason either not know or know and not unleash their biggest possible arsenal to defeat them.

#58: Characters often don't have motivations that actually tie into the plot in any way.

#59: The most powerful evil is always depicted as being present, locked away, or hidden in conspicuous places. (Asuras)

#60: Characters, if they are human, will nine times out of ten reflect the racial heritage of their authors, even if they're supposed to come from a foreign culture...

#61: "Unique" will often be used interchangeable with "original" when describing a character.

#62: Player character aliens are nearly always humanoid. Convenient!

#63: The more light-based or healing-based the magic is, the more likely the character is to be religiously-inclined.

#64: Stop me if you've heard this one before: "Her beautiful, sharp, piercing eyes..."

#65: The more strength a character has, the bigger their weapon will be.

#66: The smaller a character is, the more likely they'll rely on stealth or dexterity.

#67: ...Stealth will be handled about as well as attempting to backstab someone in broad daylight in a crowd on a podium.

#68: Despite how mechanically advanced something might be, a character will instantly understand it, or at least crudely decipher it to the point of being able to run it. Even if it would normally take years of training or is completely foreign/alien in design.

#69: All romance will culminate in sex as the ultimate expression of love, even though it isn't. Thanks Bioware!

#70: Characters who murdered their own families not only won't feel regret over it, but will generally have a completely valid excuse for why it happened, which will never come up again.
Addendum: Bonus points on the above if those parents were either maniacally abusive or so absolutely innocent as to make Jesus Christ weep with envy.

#71: If any family member hasn't been genocidally murdered off one way or another, they still won't become adventurers themselves. Only the character showed this level of initiative. Out of their entire family.

#72: Bisexual women will be far more common than bisexual men... I wonder why...

#73: The edgier the backstory, the sharper the sword. (Herzi)

#74: Characters who have riches either completely forget that they do or are conveniently separated from them.

#75: Wolverine healing powers come standard for all characters.

#76: Wounds taken will never be truly lethal wounds unless a healer is nearby who can fix that riiiight up!
Addendum: Bonus points if severe or debilitating wounds only hit limbs.

#77: Characters using melee weapons against characters who use ranged weapons across a large, open field, and who think this is a good idea...

#78: Healers never lack the resources they need to heal wounds in question. Especially pertinent if the healing is not magical in nature.

#79: Theme songs used for characters will rarely actually reflect the character in question except in some superficial manner.
Addendum: Besides, a three minute song that repeats itself three or four times should not be capable of summarizing an entire person.

#80: Characters who do sing, dance, or play instruments, are masters of their craft. Never is there just some hobbyist whose voice still cracks or who still plays the occasional wrong note.

#81: Evil characters who join a good party usually don't mesh well.
Addendum: Especially silly if the evil character in question is on a quest to do an otherwise noble deed, like rescue a princess.

#82: Characters are only rarely in positions of actual power and command over others (ex: captain) and when they are they usually don't ever think to wield that power.

#83: Admirals, generals, political savants and more are all happy to go on adventures and never have responsibilities at home that might prevent such a thing.

#84: Pets don't have minds of their own, they always obey their masters. If they don't, they immediately turn cowardly or genocidal.

#85: No character joins the campaign with an existing romantic relationship. "Sorry babe, I've gotta play hero... Cya~" (Tempest)

#86: NPC's who remark about how great their lives are going to be when they get home or when the war is over are going to die horrible, don't get attached to them-- oh, there goes Jimmy.

#87: Characters whom have a very noticeable weakness in their group (such as the lack of a warrior in a standard fantasy party) never think to just go to the local tavern and hire a mercenary.

#88: Characters all have the same level of education as their authors do, even in settings where they should have more or less.

#89: Characters of opposite genders who have a rivalry of some kind? You bet there are sexual tensions there. How could there not be?

#90: Pets, save for the purposes of scenes or being instructed to do something reside in hammer space. They're never truly in harm's way either. (Tempest)

#91: Characters go to the Leeroy Jenkins school of training and never think to set up ambushes or create formations and strategy.

#92: The party will never end up in a situation where they must sacrifice anything that would truly pain them.

#93: A character cannot lose a battle and simply be captured and and sold back. No if they are captured they will be tortured. Horrible.

#94: Tortured characters never have any scars or skin imperfections that do not in some way make them "more badass" or otherwise service to gratify their looks.

#95: Most role play characters cannot pass the SELF test: Who am I, what do I want, why am I here, how will I move on?

#96: Magic used by characters will never be used in subtle ways. The technological version of magic in science fiction has this same principle applied.

#97: Characters are either complete morons or absolute masters at the art of survivalism, which always includes tracking, hunting, cooking, skinning, sewing wounds or clothing or capes, knowing what is poisonous at a glance...

#98: Nobody seems to realize the irony of the Drow being evil black people and the High Elves being good white blonde haired blue eyed people and will play this trope straight as an arrow.

#99: Immortal characters will never "know" more about the world and its history and so on as any regular character. (ex: A 500 year old elf can only know as much as the 23 year old human.)

#100: Previous criminal associations will never bite a character in the ass later on.

#101: Never, ever, will a character ever conceive of the idea of the GM PC leading everyone into a trap, and will follow the GM PC blindly. Bonus points if they do the same for one or more other party members, even MORE bonus points if the only person they trust in the entire party is also the one they fell in love with at first sight.