1. Pluto TV: Pluto TV offers a free streaming service that includes NCIS episodes from seasons 1-6. You can watch Pluto TV through its website, mobile apps, or streaming devices like Roku, Fire TV, and Apple TV.
2. Fox's Website: Fox's website offers full episodes of NCIS for free, but you may need to create an account to access them.
3. Peacock: Peacock, NBCUniversal's streaming service, offers free access to some NCIS episodes from seasons 1-6. You can watch Peacock through its website, mobile apps, or streaming devices.
4. Tubi: Tubi is a free streaming service that offers NCIS episodes from seasons 1-6. You can watch Tubi through its website, mobile apps, or streaming devices like Roku, Fire TV, and Apple TV.
5. Local TV Stations: Some local TV stations may broadcast NCIS episodes from seasons 1-6. You can check your local listings for more information.
6. DVD Libraries: Some public libraries have DVD collections that include NCIS seasons 1-6. You can borrow DVDs from your local library for free.
It's important to note that the availability of NCIS episodes may vary depending on your region and the streaming service or source you are using.