10 Longest-Running Scripted Primetime TV Shows

With the recent debut of its 16th season — subtitled Evolution — this CBS-turned-Paramount+ procedural edged out many 15-season series in the ranking, including CSI: Crime Scene Investigation and ER. Plus, Paramount+ gave the green light to another season last month.

This Fox-turned-TBS animated comedy recently finished its 17th season, and at least two more are in the works. “It’s got a lot of rich diverse characters, and we’ve been fortunate to have some great writers along the way to keep it fresh and funny,” star Rachel MacFarlane told TV Insider last year. “The fact that it’s animated has given it the staying power. We’re aging, but our characters aren’t.”

Now that Ellen Pompeo is leaving this medical drama in its current 19th season, fans will finally see what Grey’s Anatomy is like without Grey. But the prognosis for Grey’s is promising: Its cross-platform viewership among adults 18-49 is better than any other ABC show, per The Hollywood Reporter.

With 19 seasons airing across CBS and first-run syndication between 1954 and 1973, Lassie understandably needed multiple collies to play the title role. And all of those canine stars were descendants of Pal, the first dog to take the part, according to the book Lassie: A Dog’s Life.

Coming in at 20 seasons — though with fewer episodes than Gunsmoke — is this CBS procedural, which has long since surpassed the longevity of its predecessor, JAG. And its spinoff NCIS: Los Angeles, with 14 seasons, isn’t far behind on the ranking.

Between 1955 and 1975, CBS aired 20 seasons of this Western drama, and star James Arness expected more. “We didn’t do a final, wrap-up show,” the late actor told the Associated Press in 2002. “We all expected to go on for another season, or two or three. The [network] never told anybody they were thinking of canceling.”

Seth MacFarlane’s ribald animated comedy aired its 400th episode in its current 21st season. Fox actually canceled the show after Season 3, but luckily for fans, strong DVD sales and rerun ratings soon inspired Fox to give the Griffin family another chance.

The Dick Wolf series that launched an NBC franchise, Law & Order has aired so many seasons — 22 and counting now — that it has maintained its third-place rank even with an 11-year gap between Seasons 20 and 21.

Now in its 24th season, Law & Order’s first spin-off is the last live-action scripted primetime series show that has remained in continuous production since the 1990s. SVU aired its 500th episode on NBC in 2021, with former stars returning for that milestone installment.

Created as a series of shorts for The Tracey Ullman Show, the Simpson family has been a Fox mainstay since 1989. The Simpsons is currently airing its 34th season, and its renewal means that Seasons 35 and 36 are a lock.