This is part two of Kevin Yong's "Character Creation Guide" checklist, from an article originally written for Alpha-Omega #100.

PSYCHOLOGY:
What makes your character tick?
General Personality Type: Describe your character's personality using whatever standards best apply, be it clinical psychology or literary archetypes. Type A vs Type B? Introvert or Extrovert? Phlegmatic, Melancholy, etc.?
Quirks: The kind of harmless yet odd habits that is either endearing or drives their spouse crazy. Do they alphabetize the contents of their refrigerator? Refuse to stir their tea with anything except a literal teaspoon? Always drum their fingers on their rocking chair?
Eccentricities: These are a step up from mere "quirks". They're the kind of odd behavior that makes for rumors among your neighbors and possibly interfere with day to day life. It could be odd behavior like mowing the lawn by candlelight at 2 AM, or obsessive-compulsive behavior like endless door locking or hand washing. (Note that a character dressing up in tights and leaping from rooftops in the middle of the night doesn't count as eccentric if you're writing a superhero comic, but would definitely qualify if you are working in a different genre.)
Temperament: Patient? Easily provoked? Stoic? Pessimistic and cynical? Calmly trusts in God? easily offended? Holds a grudge? Quick to anger and quick to apologize?
Method of Handling Anger: Do they yell? Curse? Send poison pen letters? Do they hold it in and give themselves ulcers? Do they simmer in resentment until they explode in response to an unrelated annoyance?
Approach to Money: Spends all their income? Spend more than their income? A balance of some savings and some debt? Is their focus on hard work and long hours? Entrepreneurial wealth creation and careful investment? Risky get-rich-quick schemes? Gambling or other questionable financial habits?
If they were suddenly made wealthy, what would they do with the money? Invest for the future? Give to idealistic causes? Pursue a dream? Quit his job and retire? Gloat? Lose it all in a short-lived orgy of riotous living?
What are their stated goals in life? From being President of the United States, or owning their own comic book studio, what are their most often expressed goal in life? What do they think would allow them to "die happy". Is your character wandering aimlessly through life? Or do they have a goal of some sort? (It doesn't have to be good goal or one that ultimately satisfies the soul -- but it sure helps keep the characters motivated in the story!) Is their life focused on a gold medal at the Olympics? To be rich and successful? To write comic books for a living? To get married and have a family? To take revenge upon the six-fingered man who killed their father?
Fears: What keeps your character up at night, worrying? Makes them nervous? Gives them the heebie-jeebies? It can be specific threats (his secret identity revealed, a family history of cancer, layoffs in their chosen career, their spouse leaving them), or it could be general situations (public speaking, being lost, going to the dentist, etc.) or more philosophical in nature (fear of wasting one's life, fear that there's no purpose to anything, vanity of vanities, all is vanity...)
Phobias: More than causing simple unease, these are psychologically crippling fears. It can be anything from claustrophobia or fear of heights, to something more exotic like a fear of peanut butter or of circus clowns.
Manias: Obsessions beyond mere hobbies or quirks. What inner motivation does the character find to be irresistible? Curiosity such that they literally can't leave a mystery uncovered? A fixation on fighting only for certain narrow causes (such as an activist obsessed with animal rights but apathetic to other human beings) or fighting only certain things (a vigilante who only targets drugs, or political corruption, or sex offenders). Perhaps their "mania" is a weird obsession, such as devoting the majority of their income and spare time on collectible figurines. What separates these from a mere eccentric hobby is a matter of degree. (For example, most of Batman's villains fall into this category, in that their obsession with riddles or coin flipping may in fact jeopardize their criminal schemes.)
Addictions: Any physical or mental crutch that they can't function without. The addiction may be as physically destructive like heroin, or destructive to family relationships like pornography, or destructive to personal time management like video game addiction, to "mostly harmless" caffeine addiction to a morning cup of coffee.
Mental Disturbances: The difference between this and the above categories depends on how technical you want to be in your psychological diagnosis. Personally, I reserve this category for actual problems within the brain rather than just behavioral issues -- that is, mind-altering afflictions like paranoia, hallucinations, bipolar disorder, etc.

How does your character treat or get along with other people? How do they handle conflicts with a spouse? Their children? Their parents? Siblings? The opposite sex in general? Children in general? Neighbors? Friends? People more successful than them? People less successful than them? Their boss? Their underlings at work? Rivals at work? With the local police? The IRS? With people who owe them something? With people to whom they owe something?
Sense of humor: Do they even have one, or are they deadly serious at all times? Do they dabble in puns? Prefer to be dry and deadpan? A prankster? Do they prefer wordplay and slapstick? Are they the kind who embarrass others with "dirty" jokes about sex or offensive ethnic humor? Can they laugh at themselves, or only at others? Is their laughter with others the good natured teasing of friends, or the mocking ridicule of a bully?
Distinctive mannerisms, gestures, habits: What is distinctive in their physical movements, posture, etc. If they were being lampooned by comedians, what traits would most likely be imitated?
Posture: Do they stand rigidly at attention? Straight but not stiff? Graceful and elegant? Slouched, slumped, and depressed? Carelessly informal and relaxed? Does their posture change with their mood, or does it stay consistent.
Vocabulary/Manner of Speech: You can tell that a character who exclaims "Golly gosh gee!" is very different from someone who routinely unleashes a barrage of foul-mouthed obscenities. A trendy teen who uses modern slang is different from a stubborn hippie who refuses to abandon the groovy-speak of the 1960s. A scientist is different from a literary critic, even if both may be elitists who enjoy using fancy big words.
Heroes/Influences: Is the character influenced or inspired by someone else? Their hero may be fictional (a child who finds courage from reading Tarzan), or historical (admiring the leadership of Abraham Lincoln), or "fictionally real" (a character in the DC universe being inspired by Superman). Their influence need not be someone famous like athletes, musicians, actors or politicians. Their role models could be a family member, friend, teacher, or a "local" hero (doctor, policeman, pastor, etc.)
Childhood/family life: How did they grow up? In poverty? In middle-class suburbs? In aristocratic wealth? With a loving yet busy hard-working family? With doting parents? Drunk or abusive parents? Was it a literate, book-loving household? Did they spend every spare moment watching TV? Did they play with their siblings, or just torment them? Was their after-school childhood spent playing with friends, participating in sports, catching up on homework, or being sent to bed without supper for the mischief of the day? How do they feel about their past? Does it match what their siblings remember? Are there facts they don't know which would change how they view their past?
Traumas from the past: What is the thing that scared him most as a child? It could be something real (getting lost while camping, bit by a dog, beat up by a bully), or something they saw (by sneaking into an R-rated slasher film when they were 8), or simply an idea that worried them (afraid of parents divorcing, afraid of growing up into a geeky fanboy). Are their childhood pains still something they resent as an adult? It doesn't even need to be an obvious trauma like physical abuse -- it could be a perceived injustice like a sibling getting nicer toys at Christmas.
Most crucial experiences: What events in your character's past shaped who they are as an adult? What shaped their outlook on life? Or on their view of God and religion? Or on morality and the rules they live by? What inspired them most? What hardships "taught them a lesson"?
What is their earliest memory? A sight, a sound, a smell, a feeling, an event, a place, a person?
Things that make them uncomfortable or embarrassed? Any talk about politics, religion or sex? Discussion of their family or childhood? Touchy-feely stuff about emotions and relationships? Is he embarrassed to discuss his work (because it's not "respectable" enough) or to be praised about it (because they're the best there is at what they do, and they won't want to look like they're gloating about it.)
What are their traits admired by others? Traits disliked by others? Are they aware of these things?
Prejudices: These can be social stereotypes they hold for racial/ethnic groups, positive or negative. It can be assumptions made about those who disagree with their politics or religion. It may also be cultural prejudices, such as that all Japanese animation is pornography, or that any Disney movie must be pop culture trash, or than any comic produced by [insert hot artist/writer name here] must be good.
Pet Peeves: What are the minor aggravations that make your character grumble, and are likely to be "the straw that breaks the camel's back" if they've already had a bad day. It could be things like telemarketers, or ATM surcharges, or noisy neighbors, or people who use emoticons in their emails. Whatever gets under your character's skin, it's the small annoyances of life are often the ones we complain the loudest about.
End of part two, to be continued.