Both of CBS’ big summer reality series begin tonight. The third season of the U.S. version of “Love Island” (CBS, 9:30 p.m.) takes place in Hawaii, after last year’s pandemic-caused landlocked season that took place on the rooftops of Las Vegas hotels. Arielle Vandenberg returns to host (that is to say, showing up every few episodes). The glue here is the narrator Matthew Hoffman. 

It follows the 90-minute, 23rd season premiere of “Big Brother” (CBS, 8 p.m.), a show that seems like it was made for a lockdown but which has already saw the elimination of one player due to a positive Covid test. Bald-headed dancer Christie Valdiserri, who certainly would have stood out amid the pack of 16, was replaced at the last minute by a 25-year-old AI engineer from Ohio, Claire Rehfuss. The cast, overall, is young and more diverse than in the past. “Big Brother” will again air Sundays, Wednesdays and Thursdays through the summer, hosted by Julie Chen Moonves. New episodes of “Love Island” this week come on Thursday, Friday and Sunday as well. 

Both Billy Crystal and John Goodman reprise their cartoon roles in a series version of the 2001 “Monsters, Inc.” called “Monsters at Work” (Disney+, streaming).