1) “Resident Alien” season-opener, 10 p.m., Syfy and USA Network. This gem is finally back, with its blend of solid scii-fi and goofy humor. Sent to destroy all humans, an alien killed the local doctor, took his body … then decided he might like people. Now some of them know his secret, one boy can see his real form (shown here) … and a more-evil alien is in town. The result, as usual, is an odd delight.
2) “The New Look” debut, Apple TV+. In German-occupied France, even the fashion designers faced ethical decisions. Christian Dior created elegance for the wives of Nazis and collaborators, while his sister worked for the Resistance; Coco Chanel closed her shop, but reportedly collaborated. In 10 richly crafted episodes, both designers go on to post-war splendor.
3) “Nature,” 8 p.m., PBS. For many of his 97 years, David Attenborough has been studying fossils. Now he watches two fossil hunters scale an English cliff, for a big prize — the giant skull of a 40-foot creature, dubbed “the Tyranosaurus of the seas.” It’s a fascinating hour, followed by a fairly interesting “Nova” portrait of the Eiffel Tower.
4) “Not Dead Yet,” 8:30 p.m., ABC. On Valentine’s Day, Cricket tries to nudge Nell back into the dating pool. That’s part of a Valentine theme for ABC: On “The Conners” (8 p.m.), Becky is hesitant to introduce her new boyfriend (Sean Astin) to her toddler.. On “Abbott Elementary” (9), Tariq is dating the mother of one of Barbara’s students. Then the “Abbott” actors do “Celebrity Family Feud,” at 9:32.
5) Valentine movies. Hallmark has a romance marathon, includiing three films (4, 6 and 8 p.m.) with “Valentine” in the title. Turner Classic Movies’ marathon peaks at 8 p.m. ET with Katharine Hepburn, Cary Grant and James Stewart in “The Philadelphia Story” (1940). And Ryan Reynolds is in both “Defiinitely, Maybe” (2008), at 6:05 p.m. on HBO, and “The Proposal” (2009), at 7:30 on Freeform.