What’s Worth Watching: ‘The Big Bang Theory’, ‘The Voice’, ‘Supergirl’, ‘Timeless’, ‘Scorpion’ and more for Monday, October 10.

The Big Bang Theory (8/7c, CBS): An instant-classic episode of the enduring hit comedy takes the relationship of Sheldon (Jim Parsons) and Amy (Mayim Bialik) to a new level—cohabitation—when her apartment floods and she moves in for what their scientific minds see as a five-week experiment in compatibility. Typically, the boys compare it to Star Trek’s original five-year mission. And as Sheldon puts it: “Now don’t be surprised if like Star Trek it’s canceled in three.” The real question, as they take over Penny’s (Kaley Cuoco) apartment, is who will annoy whom the most?

Reality Check: A big night for fans of TV’s top reality competitions. On NBC’s The Voice (8/7c), the Battle Rounds begin, and the coaches enlist an eclectic group of advisers to guide the singers: Joan Jett joining Miley Cyrus, Sammy Hagar with Adam Levine, Charlie Puth with Alicia Keys and my favorite, Bette Midler on Blake Shelton’s team. A more emotional night is expected on ABC’s Dancing With the Stars (8/7c) with each dance reflecting a celebrity’s “most memorable year,” some happy (the birth of Jana Kramer’s daughter), some traumatic (James Hinchliffe’s nearly fatal Indy 500 car crash).

Supergirl (8/7c, The CW): Same night, new network, and a very familiar face is coming to Kara’s (Melissa Benoist) aide, as her famous cousin Superman aka Clark Kent (Teen Wolf’s Tyler Hoechlin) flies in to National City from Metropolis to take on a new threat. While they happily reunite, sister Alex (Chyler Leigh) can’t help feeling like a third, less powerful, wheel.

Late Night With Seth Meyers (12:35/11:35c, NBC): If you haven’t already, it’s time to take “A Closer Look” (his signature segment) at Seth Meyers, whose barbed commentaries on the political scene have taken the former “Weekend Update” anchor to new satirical heights this year. He’s spending the week in Washington, D.C., the show’s first such road trip, broadcasting from the Warner Theatre, where he’ll welcome guests from politics, journalism and show biz (as if there’s any difference anymore). First up: the outspoken comic Sarah Silverman and CNN’s Jake Tapper.

Inside Monday TV: From the streaming world: Acorn TV cues up the second season of the acclaimed Australian political/hacker thriller The Code, with Without a Trace’s Anthony LaPaglia joining the cast. … Hulu launches the entire 10-episode season of Freakish, a zombie outbreak teen horror show. … HBO gets into the nightly news business with Vice News Tonight (7:30/6:30c). … A real-life Transparent unfolds in the POV documentary From This Day Forward (10/9c, PBS, check local listings at pbs.org), as filmmaker Sharon Shattuck tells an inspiring story of acceptance in the journey of her transgender father, who remains committed to his marriage with her mother. … NBC’s Timeless (10/9c) jumps to April 1865 on the eve of President Kennedy’s assassination, as the team wonders whether they should rewrite history or let tragic events take their course. … Shipper alert: When Walter (Elyes Gabel) accidentally flies into space in a rocket in CBS’s Scorpion (10/9c), he begins hallucinating about Paige (Katharine McPhee) while the team back on Earth tries desperately to rescue their leader.