They are monster hunters. 
Dean Winchester played by Jenson Ackles: hes a hunter. Sams older brother. hes cool, likes AC/DC owns the chevy impala, hes got humour. 

Sam Winchester played by Jared Padelecki: hes a hunter. hes sweet, nerd, tall, has a bit of humour. Deans little brother.

 Castiel played by Misha Collins: hes a fallen angel, innocent and sweet. usually monotone voice and is normally calm. Loves bees. Misses social cues and isnt too familiar with human slang and colloquialisms. 