Worth Watching: ‘Supernatural’s 300th, a ‘Grey’s Triangle, the Judys Bedevil ‘Brooklyn’

Dean Buscher/The CW

A selective critical checklist of notable Thursday TV:

Supernatural (8/7c, The CW): The ultimate never-say-die thriller reaches yet another milestone with its 300th episode, and it’s a truly special occasion when Jeffrey Dean Morgan (taking a welcome break from Negan’s tired villainy on The Walking Dead) returns to the Winchester fold as patriarch John. Look for some look-awaited emotional closure in this magical reunion as the family sits around the dinner table for the first time in 14 years, before going back on the demon hunt.

Jeffrey Dean Morgan and the 'Supernatural' Cast Take Us Inside the 300th EpisodeSee Also

Jeffrey Dean Morgan and the 'Supernatural' Cast Take Us Inside the 300th Episode

'Once we started the big scenes with the boys — who I sort of see as my sons — we just fell into it,' Morgan says of reuniting with Padalecki and Ackles.

Grey’s Anatomy (8/7c, ABC): Also from the annals of long-running TV: To think there was a time when Grey’s fans (including this one) thought the show was over when Meredith (Ellen Pompeo) lost first her soulmate, Cristina, and then the love of her life, Derek. Now well into its 15th season, soon to overtake ER’s run of 331 episodes, and not feeling anywhere near as stale or played-out as that series did by then, Grey’s finds the good Dr. Grey in a classic rom-com lust triangle, wondering which of the two hunks wooing her — surgical resident DeLuca (Giacomo Gianniotti) or new ortho head Link (Chris Carmack) —she’ll decide to date. If either. In other, less happy relationship news, Bailey (Chandra Wilson) and husband Ben (Station 19’s Jason George) come to grips with their troubled marriage. Debbie Allen, who thankfully survived last week’s surgery as Dr. Catherine Fox, is in the director’s chair.

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'Grey's Anatomy' Season 16 Renewal Very Likely, Says ABC President

Mostly because of Ellen Pompeo's two year-deal with ABC Studios.

Brooklyn Nine-Nine (9/8c, NBC): A very funny episode of the cop comedy reunites Andy Samberg’s Jake and Craig Robinson as Doug Judy (aka the Pontiac Bandit), his reformed — or is he? — car-stealing soulmate from the other side of the law. Their chemistry crackles, and it gets even better when the latest caper introduces Doug’s sister Trudy (the hilarious Nicole Byer). Most of the rest of the gang is busy imbibing at cop bar Shaw’s, site of a drink-off against local firefighters (including guest star Rob Riggle) who threaten to take over the joint.

'Brooklyn Nine-Nine' Says Goodbye to Gina Linetti in 'Four Movements' (RECAP)See Also

'Brooklyn Nine-Nine' Says Goodbye to Gina Linetti in 'Four Movements' (RECAP)

'Four Movements' places Gina directly in the spotlight and celebrates every aspect of her personality and humor.

Inside Thursday TV: The moving HBO documentary Song of Parkland (7:30/6:30c) follows the efforts of theater students and their teacher, Melody Herzfled, to carry on after the Feb. 14, 2018 mass shooting at Florida’s Marjory Stoneman Douglas High School. The drama class would eventually perform to a nationwide audience on the Tony Awards… Guest star alerts: Keith Carradine, usually seen as the president on Madam Secretary, returns to CBS’s The Big Bang Theory (8/7c) as Penny’s (Kaley Cuoco) dad. We know she’s not too thrilled about husband Leonard (Johnny Galecki) donating his DNA to help her ex-boyfriend Zack (Brian Thomas Smith) start a family, but how will her dad react? … With the restaurant about to open on ABC’s A Million Little Things (9/8c), Delilah (Stephanie Szostak) enlists Revenge’s James Tupper to help with the preparation, and something tells us there could be plenty cooking in that kitchen. But Regina (Christina Moses) is tasting only bitterness when her meddlesome mom (Romy Rosemont) intervenes… Ray Donovan’s much-missed Paula Malcomson guests on NBC’s Law & Order: Special Victims Unit (10/9c) in an intriguing episode where members of the squad wrestle with testifying against a woman on trial for killing her abusive husband.