The last five episodes of "NCIS" are available on the CBS website as of 2015. Additional full episodes of the show can be seen through CBS All Access for about $6 per month.
Less reputable websites that offer NCIS online illegally for free force viewers to download software that contains adware that makes computers run slow. This software is also notorious for carrying spyware and unwanted computer viruses.
YouTube and Hulu, which are safe for computers offer free "NCIS" clips, but not many full episodes. Cable providers such as Comcast Xfinity, Time Warner and Cox Cable offer limited full episodes, but also provide a large assortment of show clips for subscribers.
Amazon and Vudu offer "NCIS" episodes for about $2 per episode. Coupon websites offer discounts to Vudu, Hulu and Amazon, so it may be possible to watch "NCIS" for free in conjunction with these tools. For example, a Roku comes with a $5 Vudu discount, so a viewer purchasing a Roku can watch "NCIS" for free by using the coupon included with the product.
"NCIS" is a police procedural show that debuted on CBS in 2003. NCIS is an acronym for Naval Criminal Investigative Services. The popular show has been the vehicle for two spin offs: "NCIS: Los Angeles," starring former rapper LL Cool J, and "NCIS: New Orleans."