Calvin is the main character in Calvin and Hobbes and feels, like we all do at 6 years old, that the world revolves around him. He is actually quite a smart kid, he just seems to be lacking some common sense sometimes. Because of this he is constantly getting into trouble and causing havoc. Calvin often blames Hobbes for his misbehaviour which results in him ending up in more trouble.
Hobbes is Calvin's best and only friend. He is actually a stuffed toy but Calvin sees him as alive and well. He likes to pounce on Calvin and torment him with his (supposed) knowledge of everything but when it comes down to it, he loves Calvin as much as Calvin loves him.
Calvin's parents do an incredibly good job of bringing him up considering the things he gets up to. Despite this, they both often lose their temper with him but more often than not, they get the situation under control. They were childhood sweethearts and look like they'll be together for ever.
Susie is Calvin's next door neighbour and absolutely adores Hobbes. She is incredibly smart but doesn't seem to have many friends, hoping one day to become Calvin's. Calvin always tries his hardest to get one over on Susie, though this is probably because he likes her.
Rosalyn is Calvin's babysitter. She is probably the only person Calvin is frightened of, and the only person that will babysit Calvin. Calvin's Mom and Dad are prepared to pay Rosalyn's prices once in a while, just to escape Calvin for a night. It is a surprise Rosalyn continues to babysit as every time she does Calvin seems to think up a plan to cause trouble for her.
Moe is the school bully and seems to always be on the lookout for Calvin to steal his lunch money or just to beat him up. Despite this Calvin doesn't actually seem to be afraid of Moe (despite constant beatings) and quite enjoys confusing and insulting him, which isn't hard.
Miss Wormwood is Calvin's teacher and is near to retirement. She is constantly stressed out by Calvin, she smokes a lot and seems to be on medication. Because of this you actually feel quite sorry for her.
Uncle Max was brought into the strips for one week only to visit his younger brother, Calvin's dad. Whilst visiting, Calvin made a comment suggesting Uncle Max had been in jail which is why he hadn't been seen before. In fact Max was never to be seen again because he couldn't refer to Calvin's mom and dad by name as Bill Watterson wanted them to be only known as Calvin's parents, nothing more.
One of Calvin's alter ego's, Stupendous Man came about from a costume Calvin's Mom made for him. Now, every time he put's it on he becomes a comic book super hero, though he tends to save himself from work rather than saving the world from danger.
Another of Calvin's fantasy characters, Spaceman Spiff is an intergalactic hero and seems to help Calvin escape from reality the most by taking him as far from Earth as possible. He is usually found on an alien planet after being shot down by unknown forces, only to be confronted by horrible aliens.
Calvin's imagination also creates Tracer Bullet, a private investigator who drinks, smokes and carries a revolver. The Tracer Bullet comic strips are all done in black and white 'film noir' style.