The series is based on Stephen King's novella The Colorado Kid.
The actors join star Emily Rose on the show, which is expected to premiere this summer.
The series will take place in a town in Maine "where people with supernatural abilities have migrated for generations because it mutes their powers, allowing them to lead normal lives", says Syfy.
Rose plays an FBI agent named Audrey Parker, who is called in to solve the murder of a local ex-con.
Bryant (Queer as Folk, Dollhouse) is to play local cop Nathan Wuornos, who joins Parker's investigation.
Balfour (24, Six Feet Under) will portray a mysterious free spirit who lives in the town.
Filming begins this spring in Halifax, Nova Scotia. The series is slated to debut in late 2010.