CBS is celebrating the 20th anniversary of NCIS with a special event on September 25th. The celebration includes a mini marathon of the series premiere, an episode from Season 2, and a current episode with the current cast. The franchise will also reach its milestone 1,000th episode during Season 21. In addition to the marathon, fans can enjoy a 20% discount on NCIS merchandise and participate in a social media engagement through CBS's Bandium app. The NCIS franchise will also be expanding with an international edition called Sydney.