NCIS Day marathon on CBS to celebrate NCIS's 20th anniversary

On September 23, 2003, US TV audiences were first introduced to NCIS. Twenty years and more than 450 episodes later, NCIS is one of the most popular shows in TV history, with fans having enjoyed (and enjoying) various spinoffs and awaiting NCIS season 21. To celebrate all of this, CBS has declared Monday, September 25, NCIS Day to celebrate the crime procedural's 20th anniversary, highlighted by a mini NCIS Day marathon.

Starting at 8 pm ET/PT on September 25, CBS is airing back-to-back-to-back episodes of NCIS. The night starts off with the series premiere episode of NCIS at 8 pm ET/PT, then airs the NCIS season 2 finale "SWAK" at 9 pm ET/PT and concludes with a popular episode from NCIS season 19, "All Hands," at 10 pm ET/PT.

September 25 would likely have been the premiere date for NCIS season 21 had the season not been delayed as a result of the writers' and actors' strikes against the studios as they work for a new labor agreement.

With the flagship NCIS franchise and NCIS: Hawai'i season 3 both off air for the fall TV season, CBS looks to be relying on NCIS reruns to fill its Monday primetime lineup in the immediacy. However, the new spinoff NCIS: Sydney was able to complete episodes pre-strikes, and will premiere on CBS on Monday, November 13, so fans will be getting some new NCIS content this year.

There are additional perks being offered in relation to NCIS's 20th anniversary. Fans can get 20% off NCIS merchandise with the code NCIS20 at the NCIS Storefront for ParamountShop.com through October 2. QR discount codes will be shown throughout the NCIS Day marathon that viewers can access.

Some social media feature are also planned, including the launch of an @NCISverse handle across social media platforms to give fans a more immersive experience. Plus, CBS is launching their own version of the NCIS Bandium app on Facebook and Instagram that will give fans sneak peeks and early access to trailers and clips for NCIS: Sydney and more.

If you want to watch the NCIS Day marathon then you need to have access to CBS, which is available a handful of ways. There's a traditional pay-TV subscription plan, a TV antenna or a live TV streaming service that carries CBS, like Fubo, Hulu with Live TV and YouTube TV. You can also access your local CBS channel live if you subscribe to Paramount Plus with Showtime.

If you just want to catch up with NCIS or any of its spinoffs (NCIS: New Orleans, NCIS: Los Angeles and NCIS: Hawai'i), then you can do so on demand with any Paramount Plus subscription.