“Cougar Town” (7 p.m. and 7:30 p.m., ABC) will be returning for a fourth season. But not on ABC. Last week, TBS announced it would be airing 15 original episodes of the comedy starring Courteney Cox, as well as repeating the first 61 episodes from its stint on ABC.

TBS has rebranded itself as a comedy network with both original shows (including Tyler Perry’s “House of Payne”), Conan O’Brien’s talk show and endless repeats of network fare. Tonight’s TBS lineup consists of six opportunities to watch “The Big Bang Theory.” Other nights offer “Family Guy” marathons.

This hardly surprising move marks yet another step toward the rough equivalency of network and cable sitcoms — both in terms of audience size and overall quality. I was struck earlier this year that Nancy Travis’ role in the ABC series “Last Man Standing” seemed just as dated and laugh-track-driven as her turn on TBS’ “The Bill Engvall Show.” So it doesn’t surprise me that the two networks have met somewhere in the middle and are now swapping shows.

Tonight’s season finales

• A terrorist threatens to detonate a bomb on “NCIS” (7 p.m., CBS).

• Teddy’s big surprise on “90210” (7 p.m., CW).

• The Chameleon ensnares the team on a two-hour “NCIS: Los Angeles” (8 p.m., CBS).

• The top three thrash it out on “Fashion Star” (9 p.m., NBC).

• Amelia enters labor surrounded by friends, or at least colleagues, on “Private Practice” (9 p.m., ABC).

Tonight’s other highlights

• Two hours of auditions on “America’s Got Talent” (7 p.m., NBC).

• Lindsay Lohan guest-stars on a two-hour “Glee” (7 p.m., Fox).

• A repeat “American Experience” (7 p.m., PBS, check local listings) profiles Bill Clinton.

• Grim conditions take a toll on “Deadliest Catch” (8 p.m., Discovery).

Cult Choice

After muggers attack his loved ones, a thoughtful architect (Charles Bronson) turns into a violent vigilante in the 1974 shocker “Death Wish” (8 p.m., AMC). Look for a young Jeff Goldblum in his first screen credit, as “Freak No. 1.”