Paxton was among those who encountered Kennedy shortly before his death as a member of the crowd in the parking lot of Fort Worth's Hotel Texas where Kennedy gave one of his last public speeches just three hours before his death.
"I was 8 years old that day, and I remember thinking it was like seeing a movie star," the Texas-born "Titanic" and "Twister" actor said in a statement. "There stood a man at the peak of his life and his career, but little did he or any of us know that in three hours he would be murdered in cold blood."
NatGeo said the documentary "takes both in-depth and birds-eye views of the final day of Kennedy's life through first-hand accounts from people who were among the last to interact with him, oblivious at the time to their truly remarkable brush with history, along with the everyday objects whose connection to the event transformed them into priceless artifacts."
The documentary is to premiere on the cable network Nov. 8. It will also premiere on the National Geographic Channel internationally in 171 countries and 48 languages.