Kelly Kapoor is the customer service representative. She has a bubbly personality and is very talkative. She tends to annoy whoever is nearest to her. She often talks about her desire to get married and have children. She enjoys shopping online, gossiping about celebrities, and Ryan Howard.
Ryan Howard is the "temp" who later becomes Vice President of the North East region and the director of new media. Unfortunately, he was arrested for fraud (reporting his sales twice). When Pam leaves for Art School, he fills in as receptionist. He aspires to "get back on top" and even threatens to make Jim and Kevin "sorry" when he does.
Ryan wanted only a casual relationship with Kelly while Kelly said many times that she wanted to marry Ryan and have his children. They had a very troubled on-again, off-again relationship until Ryan gets promoted and dumps her. Kelly tries to get back at Ryan for dumping her by dating Darryl Philbin, the foreman for Dunder Mifflin's warehouse. Ryan merely seems mildly uncomfortable about this. 
Jim Halpert: We've already discussed him in some detail. Jim is a good salesman. He is very smart but unmotivated. He spends a great deal of his time playing pranks on Dwight Schrute. He often got Pam Beesly, the receptionist, to join in on the fun. In early episodes, Jim had an obvious crush on Pam who was at the time engaged to Roy. Jim was part of the reason that Pam ended the engagement. And Pam was the reason why Jim took the job at Stamford. By the time Pam realized that she liked Jim too, he had already started dating Karen Fillipelli, who he met when he worked at the Stamford branch. Jim finally broke it off with Karen and began dating Pam. He proposed to Pam in a recent episode and, of course, she said 'yes'.
Pam Beesly is the receptionist as I mentioned above. Pam enjoys art. This is brought up several times throughout the series. And in the latest episodes, Pam goes to Pratt Institute to study for three months. Pam is nice and modest. In early episodes she seems timid and hesitant to speak her mind but later, after breaking up with Roy, she decides to be more honest and outgoing.
Dwight Schrute is the Assistant (to the) Regional Manager. He wants to be Michael's right hand man. Dwight always wears a short sleeved button-up shirt of a mustard color and a tie. He is Dunder Mifflin's best salesman. He greatly dislikes Jim Halpert, who often plays pranks on him, and often asks for permission to fire him. Dwight always takes the responsibilities that Michael gives him and goes to the extreme with them. He seeks control over the other employees. At one point he even plots to take Micheal's job. I highly suggest reading the wikipedia article on Dwight Schrute. Especially the part about his family and childhood. It is very amusing and will give you some insight into all that is Dwight. http://en.wikipedia.org/wiki/Dwight_Schrute
Dwight's first reaction, once he realizes Jim is impersonating him, is to say "imitation is the sincerest form of flattery" and then as Jim places a bobble head on his desk (similar to the one Dwight has of himself) Dwight says " Identity theft is a crime, Jim! Identity theft hurts thousands of families every year!"
In the latest episodes, Dwight has been having an affair with Angela Martin who is currently engaged to Andy Bernard. Angela originally broke up her (secret) relationship with Dwight after he killed her aging and sickly cat, Sprinkles. Angela is an accountant at Dunder Mifflin. Angela could be described as being uptight, cold, and judgemental. She is very prim, proper, and modest. Her favorite song is the Little Drummer Boy.
Andy Bernard is the Regional Director in charge of sales. Andy is a graduate of Cornell and likes to brag about it. He enjoys making up nicknames for coworkers. In the earliest episodes that he was in he had anger management issues and was sent away for awhile. He returns to the office, requesting to be called "Drew" but everyone continues to call him Andy. Andy carried the ring he gave Angela around in his pocket for 6 years because as he says "you never know when you'll find the right girl". He is also a devoted member of an a Capella group. He brings his hobby of singing to work with him on several occasions.
As always, if I've left anything out or messed something up, let me know with a comment!
Holly Flax: She is new to Dunder Mifflin. She is replaced Toby Flenderson at the end of Season 4. She is, as I said in a previous post, much like Michael. Because she is new not a whole lot is known about her. It seems that she does like Michael in return though. So far, things are going well between Michael and Holly and that is thanks to Jim Halpert.
Karen Fillipelli: Karen worked at the Stamford branch of Dunder Mifflin (along with Andy Bernard). Karen and Jim Halpert had a relatively short relationship in past seasons. She now is the branch manager at the Utica branch.
Mose Shrute: (seen above ^) Dwight Shrute's cousin who works and lives on the family beet farm. He has few if any speaking roles. He is usually seen being awkward and timid in the background.
Roy Anderson: former fiance to Pam Beasley. He worked as a dock worker at Dunder Mifflin. They had a very long engagement (which irked Pam). He finally decides to set a date but shortly after they break up. Roy tried to fix things but in the end he encouraged Pam to date Jim.
Michael is a friendly guy but he is socially awkward. It is kind of hard to explain him. Michael views himself as being extremely politically correct but...he isn't. He tries to be though, so, I guess that is all that matters. Michael thinks that he is a great comedian. He even takes acting lessons in which he portrays his alter ego, Michael Scarn. He even wrote a screenplay staring Michael Scarn which employees at Dunder Mifflin found and read out loud one day while Michael wasn't there. The employees do not take Michael very seriously.
The latest with Michael is that his ex-girlfriend, Jan, is pregnant. But not with his child. They had a terrible relationship. Jan manipulated and abused Michael all of the time. At one moment, she would say that she wanted kids and then the next she would change her mind...causing Michael to get several vasectomies and then have them reversed again. Anyway, Jan used to be Michael's boss until she got fired for her bizarre behavior. Anyway, back to the baby. Jan went to a sperm bank behind Michael's back and it was revealed that she was pregnant in the season finale last season (4). Michael is very excited about it because he has always wanted a child.
Okay, if I've left anything out or if you have any questions feel free to leave a comment! 
Nearly every time I ask anyone if they watch The Office, they tell me that they think it is weird and not funny (well, only when they don't like it). I understand this. It is a situation comedy. You have to know the characters and the situations that they are in for it to be funny. So, before you make any judgements about it, you have to watch more than one episode. And I'd suggest starting from the beginning. Avoid starting with the newest season. It will not make sense.
