Danny Phantom: The Ultimate Enemy (6 p.m., Nick): Danny fights evil and his own dark side in this hourlong episode.
Stargate SG-1 (6 p.m., Sci Fi): The midseason finale (new episodes return in January) finds the team fighting on two fronts.
Twins (7:30 p.m., Ch. 30): Tacky and unfunny new sitcom premieres.
What I Like About You (7 p.m., Ch. 30): In the fourth-season premiere, Val wakes up with a wedding ring on her finger.
Reba (8 p.m., Ch. 30): In the fifth-season premiere, Reba begins dating a mystery man.
Living With Fran (8:30 p.m., Ch. 30): In the second-season premiere, Fran and Riley celebrate one year of living together.