1) “MasterChef,” 8 p.m., Fox. Jessica Bosworth and Jesse Rosenwald (shown here) met as Boston bartenders, almost a decade ago. Last year (when the show shifted to duos), they won the $250,000 prize … and promptly got engaged. Now, in a castle, there’s a royal-style wedding dinner prepared by the 12 home chefs.
2) “Nation’s Dumbest,” 9 p.m., Fox. This fun show has already had one surprise and almost a second one, with strong showings by singers who haven’t spent a lot of time in classrooms. First. Elle King won; then JoJo Siwa came close, before losing to Dr. Drew Pinsky. This third week offers variations on chess and school photos.
3) “The Ark” season-opener, 10 p.m., Syfy. A young crew took passengers from a troubled Earth to this new colony. Now the story is split: The colony scenes are fairly good, especially when the new sheriff has a very bad first day. The other scenes have lots of death and dismay, as the young officers try a dangerous rescue mission.
4) “Celebrity Who Wants To Be a Millionaire,” 8 p.m., ABC. First, this continues the run of Ben Affleck and “Jeopardy” champion Jamie Ding. Then we get former “Seinfeld” actors Jason Alexander and Wayne Knight and comedians Tig Notaro and Pete Holmes. “Shifting Gears” reruns follow.
5) “The Devil Wears Prada” (2006), 6:30 p.m., Freeform. The original was a delight, with great work from Meryl Streep and Anne Hathaway. (They’re also in the sequel, which is merely fairly good.) This is followed at 9 and 10 by the start of a reality show focusing on Stassi Schroeder, a writer and reality figure, formerly of “Vanderpump Rules.”