Friday Night Lights: The final season of the drama returns to the broadcast airwaves with a new school year and football season starting. Kyle Chandler, Connie Britton, Michael B. Jordan and Matt Lauria star (8 p.m. NBC).
Smallville: When Clark (Tom Welling) finds a mirror box in the barn, Clark Luthor (his alter ego) sends him back into the alternate universe, where he has an angry encounter with Jonathan (John Schneider) in this new episode (8 p.m. KTLA).
Supernatural: Balthazar (Sebastian Roche) tampers with the past by preventing the sinking of the Titanic. An angry Fate (Katie Walder) retaliates by killing those who would have died when it sank in this new episode (9 p.m. KTLA).
Fringe: Olivia (Anna Torv) could be lost forever if William Bell's consciousness occupies her body much longer, so the team scrambles to remedy the situation as quickly as possible. Joshua Jackson, John Noble, Lance Reddick and Jasika Nicole star in this new episode (9 p.m. Fox).
The Ricky Gervais Show: The animated chat show ends its season (9 p.m. HBO).
Camelot: Merlin begins his quest to find a sword fit for a king and Arthur spars with Leontes to prove himself to Guinevere in this new episode (10 p.m. Starz).
Lemonade Mouth: This new TV musical, based on a book by Mark Peter Hughes, tells the story of five teens who meet in detention and form a band. Bridgit Mendler, Adam Hicks, Hayley Kiyoko, Naomi Scott and Blake Michael star (8 p.m. Disney).
Boxing: Friday Night Fights Ivan Popoca vs. Ruslan Provodnikov, from Temecula. (6 p.m. ESPN2).