Righttt, i'll probably get a lot of this wrong but some can correct me if i am

Lex has been fascinated with Clark ever since he saved him from that car crash and he's had like loads of people research into his life. But Clark and Lex have had an on/off friendship for ages and since Lana and Clark broke up Lana got together with Lex and now they are getting married and having a baby so it's obvious the friendship is completly over.
Lionel is Lex's dad who you never really know if he's evil or not he was with Lex at the beginning but then got some crazy powers and could comunicate with Jor-el (Clark's biological father) and then he knew Clark's secret and up until now he seems to have kept it. Now he's trying to get with Martha, Clark's mum ever since Jonathon died.
Martha has just always been there for Clark, not really one of the main characters.
Clark, well he's always fighting off the meteor freaks with Chloe his best friend. He always saves people's lifes a lot fo the time it's Lana but he never could tell her the truth about him, but Chloe knows the truth, not because he told her, but because she got shown by Alisha (she was only in it for a few episodes) him stopping a car going at full speed and then following him to that big ice thing (forgot what it's called) and saw him talking to Jor-el and then he had to tell her. Clark can't be near green Kryptonite because it hurts him or something.
Chloe is the reporter who is like a whizz with computers and always has a plan to help out Clark.
Lana is the one Clark loves and always has but is now with Lex and she's getting closer to finding out his secret. She's had an eventful past with all the stuff happening with the witch coming back to life in her body (my favourtite season

) but she's getting a bit boring in the latest season.
Lois is Chloe's cousin, she's a reporter now aswell she had a bit a thing with the Green arrow (only in it for about 6 episodes, i think) she's really sarcastic and always has something to say to Clark and she recently had a fling with Clark, but only because of red K (which makes Clark a bit crazy! he's actually really mean when he's infected with that!)
Can't think of much more, but hope that's a start for you, if you want to know anything else just ask

Number 5. of the Daniel Meade fanclub