"It's Always Sunny in Philadelphia" is a show on FX about five sociopaths (called "The Gang") who run a very unsuccessful bar in Philadelphia, Pennsylvannia, called Paddy's Pub. When the Gang isn't at the bar (which is most of the time; the two or three regulars at Paddy's Pub usually serve themselves), they're off on crazy ventures that often put innocent bystanders, each other, and themselves at risk. Though the members of the Gang are ostensibly friends, they often manipulate and backstab one another in pursuit of their own personal goals, which can include deciding who to put on a billboard, how to deal with bums pleasuring themselves in the alley, and discovering who pooped in a bed.
Here's a rundown of the Gang (from top to bottom):
Rob McElhenney as "Ronald 'Mac' McDonald" - The "sheriff of Paddy's", Mac is a supposed bouncer who believes he is much more capable at martial arts than he really is. Whenever he fails at pulling-off a karate move or back-flipping up a wall, Mac is quick to offer an excuse as to why he couldn't perform such a feat at the time. Mac longs for the love and attention of his father, Luther; however, he has also had Luther arrested, so whatever. Mac lives in an apartment together with Dennis (Dennis, BTW, apparently spies on Mac's room whenever Mac has a lady friend over); however, he is a childhood friend of Charlie's as well (as they are both "white trash").
Danny DeVito as "Frank Reynolds" - The father of Dennis and Sweet Dee (or is he?), Frank joined the Gang in season 2. Frank amassed great wealth through shady and corrupt business methods, but has since decided that he wants to abandon the upper class lifestyle. While he originally intended to give his money to charity, Dennis and Sweet Dee convinced him to hang on to it (hoping they could inherit it). Frank now lives with Charlie and has taken over ownership of Paddy's Pub, using his expertise at cooking the books to somehow wring a profit out of the bar. As such, the rest of the Gang is nearly completely dependent on Frank for money (which he is usually happy to provide, except when he's not).
Glenn Howerton as "Dennis Reynolds" - A self proclaimed playboy, Dennis Reynolds could be said to be the brains of the Gang. Dennis isn't very smart, and most certainly not wise, but he has a great amount of charisma. Out of all the members of the Gang, Dennis is the most sociopathic; he's perfected a system of manipulating women emotionally into having sex with him, can cry on cue, was flattered when Charlie compared him to a serial killer, and even let slip to Mac that he hasn't had "feelings" since high school. Dennis has also written an autobiography, "Dennis Reynolds: An Erotic Life", which describes his sexual exploits and recounts how Christ-like stigmata wounds manifested on his palms.
Charlie Day as "Charlie Kelly" - The janitor of Paddy's Pub, Charlie is unintelligent, ignorant, and nearly illiterate, but perhaps the nicest person out of the entire Gang (that's still not very nice). Charlie lives in absolute squalor; he has to eat cat food and huff glue to sleep (because of all the howling cats outside of his window; the cat food and glue make him really sick, but also tired enough to sleep despite the cats), he uses a coffee can instead of a toilet, and he isn't above eating out of the garbage. Charlie also stalks a girl known only as the Waitress, seeking an opportunity to earn her love (he has so far failed miserably; telling her he had cancer when he really didn't certainly didn't help). Frank decided to move in with him after abandoning the upper class lifestyle; the pair have since formed a strong friendship and enjoy enriching activities such as dumpster diving and crawling around at night pretending to be worms.
Kaitlin Olson as "Deandra 'Sweet Dee' Reynolds" - The waitress of Paddy's Pub and supposed "professional actress" (she can't say more than a sentence on stage before dry heaving), Sweet Dee suffers nearly constant emotional, financial, and sometimes even physical abuse from the rest of the Gang. They Gang has stolen Dee's life savings out of her sock drawer, totaled her car, had her next car stolen, and have even poisoned her (just after telling Dee that they were proud of her) as part of their schemes. Despite all this, Dee continues to hang out with the Gang. Dee sometimes brings her only other friend, Artemis (Artemis Pebdani), into the Gang's plots, but not even Artemis is above abusing Dee (who, in her own words, is a "slutty whore bitch"). Dee is also partially responsible for the continued degradation of Matthew Mara aka Rickety Cricket (David Hornsby), a former Catholic priest turned bum, who was infatuated with Dee in high school (despite her back brace).