Johnston Jacob "Jake" Green, Jr., (portrayed by Skeet Ulrich) is the oldest son of the Green family and the protagonist of the series. Jake was once a member of John Brady's group of survivalists; and, after a botched armed robbery job, in which Chris Sullivan (Jonah's son and the brother of Jake's girlfriend, Emily Sullivan) was killed, Jake fled Jericho. Five years later, Jake returned to Jericho to pay his respects to his recently deceased grandfather and to claim the money his grandfather left him. Because of the problems in their relationship, his father refused to hand over the money; and Jake was leaving town again when he witnessed the destruction of Denver.
Jake was initially an unlikely hero, but his checkered past helped in Jericho's trying times. He took charge of getting people to safety, and eventually people came to look upon him as a leader. Over time, he and his father repaired their relations. With his father's blessing, Jake put together the Jericho Rangers to help keep Jericho safe. Jake frequently left Jericho for supplies or information and on other missions—including rescuing his brother from New Bern, training the Rangers in gun skills, and defending the town from Ravenwood, a private military company, and the New Bern militia, and any other threats. Although he is impulsive, he is also intelligent, often coming up with ideas that help the town to survive. Jake is a skilled aviator thanks in part to his flight school training and also what his grandfather taught him.
In Season 2, with the garrisoning and reconstruction of Jericho by the Allied States of America (ASA) Army, the area's military commander and chief administrator, Major Edward Beck, recognized Jake's role as "the guy"—the one the others follow and listen to in the heat of conflict—and appointed him Sheriff. Jake and the rest of Jericho witnessed the domination of the ASA and Jennings & Rall (J&R) over the town and the country at large, with Jake knowing first-hand how dangerous J&R was when it came to business dealings. Having previously been deliberately misleading and vague about his past, Jake came clean to Eric and explained what he did during his absence: Jake served as a private military contractor for Jennings & Rall in Iraq and Afghanistan. He left the service of J&R and vowed never to return after he took part in a massacre in Iraq with other Ravenwood soldiers; and his passport is flagged for non-cooperation on an undercover mission against Ravenwood. The incident has continued to haunt him, as he killed several innocent civilians, including a little girl.
Jake secretly worked with John Brady, whom he eventually saw as a friend, to get the last remaining nuclear bomb from the September Attacks to the Independent Republic of Texas, thus exposing the conspiracy behind the attacks. The Cheyanne government (ASA) and Jennings & Rall had covered up the true culprits of the September Attacks and blamed it on North Korea and Iran which they bombed out of existence. In getting the last bomb to Texas however, Jake Green and Robert Hawkins inadvertently started the Second American Civil War with Texas siding with the Columbus government (USA) in the coming war.