SPN refers to a fabulous TV show on the CW, Supernatural
. It is about two brothers, Sam and Dean Winchester, who fight evil stuff from real things we've all heard of (eg, bloody mary
, mainly demons though). It's scary but enternaining. There are Deangirls and Samgirls and Slash fans (Sam/Dean aka wincest
Supernatural is an American supernatural and horror television series created by Eric Kripke, which debuted on September 13, 2005 on The WB, and is now part of The CW's lineup. Starring Jared Padalecki as Sam Winchester and Jensen Ackles as Dean Winchester, the series follows the brothers as they hunt demons and other figures of the supernatural.
Other characters come and go as we go along, for example John Winchester, their father, was a main character for the first and second seasons, from season 4 upwards Castiel is a major character and Bobby is major from around season 2, Ruby is a major character from around season 2 as well, i think.