What you do is pick a listing of characters you feel comfortable writing/working with and number all of them.  Then use a random number generator (random.org is great for this) for however many you have and roll to see which person falls into which category. Ignore gender and just go for it!!!

Horror movie:

The first one to die: Kwangmin

The ty best friend: Jimin

The jock:Youngmin

The : Jackson

The hero: Donghyun

The one who saw it coming (and tried to stop it): Hansol

The conspirator: Rome

The murderer all along: Eli

Chick-Flick:

Main Character: Kwangmin

Best friend: Sehyuk

Plucky Gay best friend: Zelo 

Boy-next door (who’s the right one in the end): Jimin

Bad-boy love interest: Eli

Girl that hates main for some stupid reason: Ailee

Hateful girl’s best friend (debatable friendship for main girl): BJoo

Martial Arts:

Girl worth fighting for: Gyuri

Hero/Chosen One: Jenissi

Rival friend: Zelo

Clumsy friend: Yuri

Master: Karam

Lackey: Jessica

Evil mastermind: Hakyeon

Fantasy(ish):

Kind, but absent-minded ruler: TK

Prince (hero): Xero

Spoiled, but well-meaning sibling: Jenissi

Low-class best friend: Jungkook

Evil advisor: Kwangmin

Evil advisor’s wise-cracking sidekick (may become good): Leo

Love interest (usually from the wrong-side of the tracks): Karam

Love interest’s best friend (distrustful of hero): Hoya

Anime:

Main character: Zico

Girlfriend/boyfriend: Donghyun

Overly endowed friend: Eli

Androgynous friend: TK

Spaz: Jessica

Misunderstood bully: Jungkook

Crazy usually power hungry/sadistic villain: Sungjong

Madly in love but ignored lackey to villain: Hoya

Fantasy (alternate option):

Hero: Sungjong

Wannabe hero: Jungkook

Love interest: Hoya

Mysterious ally: Youngmin

Old advisor: Hyuna

Bitter outcast: Karam

Villain: Changjo

The real mastermind after the villain dies: Jimin

Adventure: 

The hero: Rome

The sidekick: V

The useless ‘damsel’: Donghyun 

The fool: Changjo

The faux-villain: Jungkook

The wise mentor: Sungjong

The traitor: Karam

The actual villain: Jenissi

Sci-Fi:

Hero: Hakyeon

Love interest (invariably royalty):  Hansol

Best friend (smartass with big money dreams):  Jungkook

Rebel Sidekick (either for Hero or best friend, well meaning):  Eli

Teacher/Mentor: TK

Agent of the Evil-Federation (to give face to the “federation”): Jackson

Robot/Cyborg (on the side of good): Zico

Robot/Cyborg (on the side of evil) (all Sci-Fi needs robots): Sehyuk 

Traitor-Agent for the Evil-Federation (will probably die with a change of heart): Hoya

Western:

Back for vengeance hero: Donghyun

Widow(er) love interest (usually unrequited): Changjo

The innocent one: Jackson

The gambler/drunk: TK

The sheriff (potentially crooked): V

The outlaw/bully (generally has a group of followers):  Hakyeon

The villain who killed everything the hero ever loved: Leo

Post-apocalyptic:

Hero (can solve major crisis/bring a bit of peace): TK

Villain (rich because of circumstances): Sungjong

Love interest (possible “belonging” of villain, perhaps offers inside information/assistance): Eli

Sidekick (makes meager living before “rescued by considerably more collected hero): Jessica

“Evil” rival (revels in chaos/doesn’t want fix): Jackson

Rival’s love interest (also loves chaos): Kwangmin

Traitor (pretends to join hero to either usurp glory of “fix” or to try to become kingpin): BJoo

Bystander (doesn’t want to be involved but is swept into things, unlikely saver-of-the-day): Hoya

Superhero:

Hero: Changjo

Nemesis: Karam

Love interest that may or may not be a superhero as well: Zelo

Jealous human/superhero friend: Zico

Resident scientist/technology buff: Hoya

Turncoat who starts off as good and then defaults at the end: Yuri

Neutral party who doesn’t want to pick sides but usually defaults to good guys: Xero

Aging father/mother figure (could potentially die depending on whether they are human or not): Jimin