Dr. Jackson David Byron is the hidden main villain of 2004 horror film Anacondas: The Hunt for the Blood Orchid. He is 25 years old and played by Matthew Marsden.
Jack was part of a team of pharmaceutical researchers along with Gordon Mitchell, Samantha "Sam" Rogers, Gail Stern, Cole Burris and Ben Douglas, who went to a jungle in Borneo to search for the "blood orchid", a flower with miraculous effects. They arrive in a deserted native village, where everyone except Jack decides to abandon the orchid quest and to build a raft to leave the jungle. After unsuccessfully trying to convince Gordon to continue the expedition, Jack uses a poisonous spider to paralyze him, and an anaconda devours him a few moments later. Hearing his screams, the others go help him while Jack steals their raft, then he goes find the orchids.
Later, Jack succeeds to find the blood orchids above an anaconda pit. The rest of the team comes to recover the raft, but Jack points a gun on them and oblige them to accompany him to the orchids. He then shoots Bill in the arm and forces Samantha to retrieve the orchids. However, after she did it and gives the backpack containing the orchids to Jack, Bill attacks him and the backpack falls into the pit. Jack manages to beat Bill and tries to seize the backpack, but his spider escapes its jar and paralyzes him. He falls into the pit and is devoured alive by the anacondas.