|Out of universe information|
- "I thought I lost him four years ago. Since then, we've been closer than we ever were in my whole life. In a way, Selmak gave me the father I never thought I'd know."
- —Samantha Carter
Jacob grew up in Pittsburgh and joined the Air Force Academy. During a tour in Germany, he met Debra Nielson on a late night train ride. Two years later, he proposed and they were married. When Samantha was young, he was supposed to pick up Debra but was late and she was forced to take a cab. There was an accident and she was killed. Mark blamed his father for this and the two didn't speak for many years. (RPG: "Friends and Foes: Stargate Season Two") (SG1: "Secrets", "Seth", "The Devil You Know")
Jacob soon learned that he was afflicted with lymphoma, a rare form of cancer. Jacob believed his daughter's greatest dream was to become an astronaut, and he made it his business to make certain she followed her dream. He took offense when she rejected his offer for help in getting into NASA, not knowing the true nature of her work on the Stargate program. He could not believe she would prefer being locked inside Cheyenne Mountain analyzing "Deep-space radar telemetry." (SG1: "Secrets")
When Major General George S. Hammond, Captain Samantha Carter, and the Tok'ra offered blending with Selmak, Jacob could not believe what he was hearing -- but was eventually willing. He traveled through the Stargate and became host to Selmak, as well as taking the title of liaison between the Tok'ra and Tau'ri. Since blending, his perceptions of the universe have forever changed. Jacob has become far wiser and less stubborn, though also more arrogant than Sam would have wanted. (SG1: "The Tok'ra, Part 1", "The Tok'ra, Part 2")
When Charlie was sent to Stargate Command by the Reetou Central Authority, the SGC contacted the Tok'ra. He was sent and once informed of the situation he sent for Transphase Eradication Rods. He then used them to illuminate Mother. Later, he traveled with SG-1 to a planet with the Reetou Rebels. They discovered hundreds of rebels present and returned to Earth. When a squadron of five rebels followed them, he was part of a team consisting of Captain Samantha Carter and Chu that was sent to hunt them down. He was wounded by one of their Multiphasic blasters but survived. After all the Reetou were eliminated he took Charlie to the Tok'ra to cure his failing health with a Symbiote. (SG1: "Show and Tell")
A short time later, he came back to Earth to acquire the assistance of SG-1 in hunting down the Goa'uld Setesh as well as resolve the tension with his son Mark Carter. Dr. Daniel Jackson was able to locate him on the Bureau of Alcohol, Tobacco and Firearms database. They traveled to a town near Seattle and encountered Special Agent James Hamner who had them escorted out. Colonel Jack O'Neill called the President of the United States who called Hamner and put O'Neill in charge. Since Jacob or Teal'c could not get close because of their symbiotes, O'Neill, Captain Samantha Carter and Daniel went in alone. They were captured and exposed to Nish'ta. Once the organism penetrated their tissues Jacob used their earpieces to shock them and kill the Nish'ta. When they escaped and began releasing the cult members, Seth attempted to escaped through the underground passage by blending in with the cult members. He was informed by O'Neill and went to the tunnel with a Kara kesh. He found Seth who was able to use his Kara kesh on him first and force him against the wall. He then handed the Kara kesh to Samantha who used it to kill Seth. After recovering from his injuries, he and Samantha went to visit Mark and his grandchildren. (SG1: "Seth")
While on an undercover mission to discover the size of Sokar's armies, he was captured and sent to Netu. When SG-1 and Martouf came to rescue them, he informed them that Sokar's armies are ten times as big as previously thought. Martouf relied the information to Teal'c who informed the Tok'ra High Council. After Bynarr was killed by Apophis, they attempted to escape but were captured. After Martouf and SG-1 were tortured, they were able to escape by using the Transportation rings to ring to the Tel'tak. (SG1: "Jolinar's Memories", "The Devil You Know")
When Colonel Jack O'Neill and Teal'c were trapped in the X-301 Interceptor after the Recall device took them in deep space, he was on a mission to P2C-257. When Major Samantha Carter and Dr. Daniel Jackson arrived to seek his assistance, he ringed them onto his cloaked Tel'tak. After giving them a stern lecture, he agreed to help and he modified the hyperdrive to get there faster. Once there, he ringed them in the ship after they ejected from the X-301. (SG1: "Tangent")
After returning to Earth he stayed there until the Tok'ra intercepted the transmission by Apophis and Heru'ur about an alliance. He and SG-1 used his Tel'tak to travel to the Tobin system and reprogram a Tobin mine. Once the mine was reprogrammed, they released it and it attacked Apophis' mothership. Believing it was Heru'ur that attacked, Apophis revealed a cloaked fleet and destroyed Heru'ur's Ha'tak. (SG1: "The Serpent's Venom")
When SG-1 captured Cronus' Ha'tak, he gave them flying lessons in exchange for allowing the Tok'ra to use it to take the Vorash Stargate to an Off the grid planet and form a permanent Tok'ra base. When Tanith escaped and informed Apophis of the Tok'ra's location, he and Major Samantha Carter devised a plan to cause Vorash's sun to go supernova by injecting a Stargate dialed to P3W-451. The Black hole on the other side pulled matter from the star through the Gate and cause it blow. They entered hyperspace but the nova amplified the hyperspace window and their Ha'tak and Apophis' mothership were thrown to another galaxy.
Once there, Apophis' mothership was attacked by a Replicator patrol ship which allowed Jacob to flee and hide near a Blue giant to effect repairs. Once they were finished, the other ship was gone and Apophis' mothership had been abandoned. They ringed over to the mothership to acquire crystals to repair the hyperdrive. They then detected a Tel'tak and were hailed by Teal'c. They allowed them on board and Teal'c betrayed them because he was brainwashed by Apophis into believing he was still his First Prime. Once Apophis took over the ship, he entered hyperspace and throw SG-1 and Jacob in a cell. Unfortunately, a Replicator managed to sneak aboard and began to take over the ship. They increased hyperdrive speed and a power failure allowed them to escape their cell. They made it to the Tel'tak and devised a plan to stop the Replicators. Colonel Jack O'Neill and Carter headed to the engine room and when the ship dropped out of hyperspace they destroyed the Sublight engines and raced back to the Tel'tak. They escaped the ship and without the sublight engines to slow down the ship crashed into Delmak killing Apophis and destroying the Replicators. (SG1: "Exodus", "Enemies")
Jacob then spent the next few months establishing himself as a minor Goa'uld in the service of the System Lord Yu. He used this cover to get Dr. Daniel Jackson close enough to Yu to stick him with the Reol chemical to convince him he was his lo'taur Jarren. He then followed Daniel and Yu to the Hasara space station in a Tel'tak and waited for Daniel to contact him with a Short range communicator. He advised Daniel to use the poison but Daniel wanted to try to capture Osiris so the Tok'ra could remove him from Sarah Gardner. When Daniel failed to capture her he fled in an escape pod and Jacob picked him up in the Tel'tak. They traveled to Revanna and entered the atmosphere but were discovered by Death Gliders and shot down. They meet up with the rest of SG-1 and Lantash who entered the body of Lt. Kevin Elliot. Lantash used the Symbiote poison to kill the Jaffa and he and SG-1 escaped through the Stargate. (SG1: "Summit", "Last Stand")
When Dr. Daniel Jackson was exposed to Naquadria radiation poisoning, he came to Stargate Command to attempt to heal him with the Goa'uld healing device but was told to stop by Daniel so he could ascend. (SG1: "Meridian")
When Anubis' Ha'tak entered Earth orbit, he joined SG-1, Major Paul Davis and Dr. Friesen on a mission to investigate. They determined the ship was empty and ringed aboard. They headed to the Pel'tak and discovered the self-destruct had been activated and was stalled halfway through the countdown. Davis and Major Samantha Carter went to the computer core to try and shut down the self-destruct. He activated the Life support systems and unknowingly released three Jaffa. The Jaffa killed Friesen and headed to the Pel'tak. They shot Jacob in the shoulder and set the ship to crash into the atmosphere. They then ringed to the Tel'tak and were killed by Teal'c but the ring controls were destroyed in the fight. Unable to escape they crashed into the Pacific Ocean. They were rescued by Teal'c and Jonas Quinn in the Mini submarine. (SG1: "Descent")
When Anubis attacked the Tok'ra base in the Risa system, he evacuated to the Alpha Site and was shot in leg by a Staff weapon. When the Naquadah generator was tampered with, he used the Za'tarc detector to test the Tok'ra personnel. After Ocker was killed, he scanned Artok and found he was deceiving the machine. After it was discovered that Anubis' Ashrak was responsible he helped secure the Stargate until the Ashrak was killed by Bra'tac. (SG1: "Allegiance")
When Teal'c and Bra'tac encountered the Kull warrior and managed to kill it, he came to Stargate Command to preform and analysis with Major Samantha Carter. They determined the Kull armor completely protected it from energy weapons and that it died of a heart attack. He determined that the host was grown and brought to life by the Ancient healing device. He helped Dr. Daniel Jackson find the location of the device in southern Honduras. After SG-1 and Bra'tac captured a Kull warrior, he used a Memory recall device to find the location of Tartarus, where he was created. He then used the Kull armor to get past the Stargate shield on Tartarus, and infiltrated the base. After being found by Thoth, who believed he was a damaged Kull warrior, he was able to get away and deactivate the sensor array and allow Samantha and Teal'c entry into the base. Once inside, they found Anubis' queen and set C-4 to kill her. They then discovered that Anubis had already created thousands of Kull warriors and then were discovered by Thoth. Samantha killed Thoth and they fled to the Tel'tak. They were followed by many Kull warriors and one boarded the ship. It shot Teal'c in the side and knocked Samantha to the ground, it chased him to the back and Bra'tac used the Transportation rings to eject it from the ship and they traveled back to Earth. (SG1: "Evolution, Part 1", "Evolution, Part 2")
He and Major Samantha Carter were using the Ancient healing device to create the Kull disruptor on the Alpha Site, when it was attacked by Kull warriors. He and Samantha were able to kill one warrior with the disruptor and flee into the woods. He was injured by a falling tree when the self-destruct blew. He was found by Colonel Jack O'Neill, Dr. Daniel Jackson, and Teal'c and taken back to Stargate Command. After receiving medical treatment for his injures, he attempted to quell the dissent between the Tok'ra and Jaffa Rebellion but was unable to stop the dissolution of the alliance. He also got into a heated argument with Delek for not informing him of the spy within Olokun's ranks. (SG1: "Death Knell")
When the Replicators began attacking the Goa'uld, he came to Stargate Command to warn Brigadier General Jack O'Neill. He brought a Tok'ra subspace receiver to monitor the Tok'ra Operative Network which could track Ha'taks in battle. He wanted to inform Ba'al that his current strategy was unwise but O'Neill would not allow it because he would fall back to Dakara and crush the Jaffa Rebellion. When Ba'al informed the SGC of the Dakara superweapon, he and Lt. Colonel Samantha Carter traveled to Dakara to find the weapon. They were able to translate the Ancient text in the Temple of Dakara and uncover the weapon.
He discovered that the device could be reprogrammed to destroy the Replicators and with the help of Ba'al, who managed to dial every Stargate in the galaxy, they destroyed the Replicators. After doing so Selmak fell into a coma. So after the victory, Selmak couldn't save his host from dying with him. Selmak had offered to do so before the battle, but Jacob had him hold on knowing the consequences as he felt they might need Selmak's help. Jacob died in 2005. He also stated to his daughter, before dying, when she was saying she was already happy with her nearing wedding, not to let a rule ruin her life, hinting that she was in the Air Force because of him, and that she could have what she had always wanted, obviously referring to Jack, showing he was aware she had some feelings for him. (SG1: "Reckoning, Part 1", "Reckoning, Part 2", "Threads")
- In an alternate timeline accidentally created by SG-1, Jacob Carter was killed in the Vietnam War in December 1969 when his daughter Samantha Carter was less than two years old. His plane was shot down by the Viet Cong. While he managed to bail out, his parachute failed. His wingman, Lieutenant George Hammond, was unsuccessful in his attempt to rescue him. He later brought Jacob's body home to his family. (Stargate SG-1: Moebius Squared)