Lyra Belacqua is the novel's main protagonist.  She is an 11 year old girl.  She is incredibly brave and curious.  

Pantalaimon is Lyra's daemon.  He is a shape shifter, but he will eventually choose a final form.  In the story, a daemon more or less is a physical representation of a character's soul.  

Lord Asriel:  He's one of the bad guys.  Oh, he is Lyra's father too, but she doesn't know that at first.  That makes him Lord Vader and Lyra young Skywalker.  

Mrs. Coulter: Lyra's mom.  She's also evil and has a golden monkey for a daemon. 

Iorek Byrnison: He's a big armored bear.  He and Lyra work closely together as the novel progresses.  

Lee Scoresby: His profession is "aeronaut," meaning he flies hot air balloons.  He's also a friend of Iorek's.  Pullman paints him as a caricature of an old west cowboy. 

"I'm a simple aeronaut, and I'd like to end my days in comfort. Buy a little farm, a few head of cattle, some horses... Nothing grand, you notice. No palace or slaves or heaps of gold. Just the evening wind over the sage, and a ceegar, and a glass of bourbon whisky." 

Serafina Pekkal: Queen of the witch clan. She's really old, but looks young. She was in love with Farder Coram.

Farder Coram: He's a "gyptian" elder.  He's very smart, and other characters revere his wisdom.  

John Faa: Leader of the gyptians. 

Other characters are Roger, Ma Costa, and Iofur Raknison.