1) “Finding Your Roots” season-opener, 8 p.m., PBS. After growing up among Hollywood privilege, Mia Farrow (shown here in her movie days) and Anjelica Huston each lost a parent at 17. The deaths — Farrow’s dad, Huston’s mom – left them knowing little about half their roots. Now they get unsettling news: Farrow’s grandfather sent his wife to a mental home, where she died at 27. Huston’s ancestor fathered four slaves; his will freed them … but not until they were 30. It’s a fascinating hour that also traces Isabella Rossellini.
2) “The Flash” debut, 8 p.m., CW. Barry and Iris were shattered by the departure of their daughter-from-the-future. Now they’ll have to wait through the whole conception-pregnancy-birth thing before seeing her again. There’s little time to brood, in this fun and fast-paced (albeit perplexing) hour: A black hole is haunting a junkyard and a coffee shop …. A scientist has a live-forever scheme …. And the relationship is changing between Caitlin Snow and Killer Frost, who are time-sharing one body.
3) “Mixed-ish,” 9:30 p.m., ABC. Tracee Ellis Ross joins three of her “Girlfriends” co-stars – Golden Brooks, Persia White and Jill Marie Jones. That’s in ABC’s “casts from the pasts” week. “The Conners” (8 p.m.) has Dan Aykroyd with John Goodman, his “Blues Brothers 2000” co-star. “Bless This Mess” (8:30) has Michael Ian Black with Lake Bell; they co-starred in “Wet Hot American Summer.”
4) “NCIS,” 8 p.m., CBS. The season-opening two-parter is done now. Ziva returned, tricked a terrorist and vanished again … promising she’ll eventually tell Tony she’s alive. Now Sloan (Maria Bello) wants the others to talk about what happened; also, a Marine’s body is found hidden under an 18-wheeler.
5) “This Is Us” (NBC) or “Batwoman” (CW), 9 p.m. On NBC, Randall faces a tough choice and Kate and Toby adjust to their new hone; also, flashbacks show the friendship of Jack and Miguel. And CW reruns its terrific “Batwoman” pilot; the second episode, another good one, is 8 p.m. Sunday.