Highlights among returning series, by night:
1. "The Voice" kicks off its fifth season by bringing back Christina Aguilera and CeeLo Green at 8 p.m. on NBC. The show will amp up the star power by giving partners to the coaches. The most interesting pairing features Cher with Blake Shelton. Ed Sheeran will help Aguilera. Ryan Tedder joins Adam Levine. And Miguel partners with Green. Two hours on Monday are followed by two hours at 8 Tuesday.
2. "How I Met Your Mother" starts its ninth and final season with back-to-back episodes at 8 on CBS. Orlando's Wayne Brady returns as James, Barney's brother. The other guest stars include Sherri Shepherd of "The View" and Roger Bart of "Desperate Housewives."
3. "Castle" starts its sixth season at 10 on ABC. The main issue: Will Beckett accept Castle's proposal? Lisa Edelstein ("House") plays a federal investigator. The ABC drama must face off against two of the fall's most heavily promoted newcomers, "The Blacklist" on NBC and "Hostages" on CBS.
2. "Person of Interest" starts its third season with the team trying to help a naval officer in jeopardy during Fleet Week. Enrico Colantoni and Max Martini guest star in the CBS drama, now at 10 p.m. Tuesdays.
3. "Chicago Fire" opens its second season at 10 p.m. on NBC with guest star Michelle Forbes as a consultant from the state fire marshal's office. The main plot: An arsonist is going after Lt. Severide (Taylor Kinney).
1. "Modern Family" opens with back-to-back episodes at 9 on ABC. In the first, Phil and Claire plan for time away from the children. In the second, Claire returns to work, and Manny and Luke enter high school. Where did the time go?
2. "Nashville" begins its second season at 10 on ABC with a health update on Rayna (Connie Britton), who was badly injured in a car crash. Juliette (Hayden Panettiere) remains obsessed with her career, reminding us that some things never change.
3. "CSI" kicks offs its 14th season at 10 on CBS with the hunt for a ritualistic killer who has kidnapped one of the team.
1. "The Big Band Theory," TV's most popular sitcom, opens its seventh season with two episodes at 8 on CBS. In the first, Penny and Sheldon grow closer while Leonard is away. In the second, Leonard returns from the North Sea. The guest stars include Regina King as the university director of employee relations and Kevin Sussman as the owner of the comic-book store.
2. "Grey's Anatomy" begins what ABC says will be a "monumental" 10th season. In the two hours starting at 9, the hospital struggles with the storm aftermath and injuries from a mudslide. ABC teases: "Meredith is faced with a tough decision that will affect the life of a loved one."
3. "Elementary" goes to London to start its second season at 10 on CBS. Rhys Ifans comes aboard as Mycroft Holmes, Sherlock's brother, who will spill secrets.