Colonel Jeff Tracy is an unseen, yet often referenced character from the Thunderbirds Are Go! television series. He became a multi-billionaire as an astronaut, he took part in multiple outer space operations such as the construction of lunar bases like Shadow Alpha 1 and becoming the first man to walk on the planet Mars. He is the father of the Tracy brothers, and the man who created and led International Rescue, doing so after his retirement with the money he made.
Jeff Tracy went missing whilst on a mission to find information on The Hood. His ship was attacked by the villain and it sank to the bottom of the ocean. Whether or not Jeff is dead is unknown, but The Hood likes to think he is.
Jeff and Captain Lee Taylor were the first two men to land on Mars, after many months traveling to the planet their descent through the atmosphere was almost aborted after a huge dust storm was consuming the planet. However Jeff and Lee decided to take the risk and attempt a landing with Jeff claiming "humanity never got anywhere by taking it easy!" After they were successful Jeff took the first step on the planets surface making history as they both began surveying the land looking for possible signs of life. Jeff's first footprint was preserved by being encased with a glass dome placed over it where it would remain for centuries to come. A few decades later a mars colony base was built just next to Jeff's original landing site for families to live and begin a new life, Captain Lee Taylor later returned to their original site to admire his friend's footprint and the landing they had first made history on all those years before.
Although he is missing in action, Jeff still holds a massive presence on Tracy Island even if he is not there in person. He is greatly missed by the residents on the island but is remembered fondly by all that knew him well. His desk acted as a shrine as a way of keeping Jeff's memory alive.
As the father of five young sons, it is apparent that he loved each and every one of his sons equally. According to his youngest son, Alan, Jeff insisted that all the kids on the island (this includes Kayo) learn Morse Code which Alan thought was a massive waste of time until he and Kayo found a use for it.
It is assumed that Jeff loved his mother just as much as his sons. After his disappearance, Grandma became head of the family while Scott took over as Head of International Rescue. According to his second-youngest son, Gordon, Jeff always took Grandma's side when it came to her dreadful cooking and that his desk acted as a safe haven for the boys whenever Grandma tried to feed them her cookies.
At some point in time when his sons were still young, Jeff would take into his care a young British girl named Tanusha Kyrano who would later be nicknamed Kayo. While it is unknown as to whether Jeff officially adopted Kayo, he loved her as if she was his daughter and took into his confidence along with Grandma, Kayo's relationship with The Hood which he requested be kept a secret from the boys, in fear that the news might be a distraction. He allowed Kayo to live on Tracy Island with him and the other members of the Tracy family.
Brains was a close friend of Jeff's. Due to the inventor's interest in machines, Jeff asked Brains to move to Tracy Island as a member of the family and employed him to construct the five Thunderbird ships and Lady Penelope's car FAB 1 for International Rescue's usage. Sometime before or after Jeff disappeared, Brains created Thunderbird Shadow for Kayo.
Lady Penelope and Parker are longtime friends of Jeff's. He asked Penelope and Parker to join IR as special agents. According to Parker, he [Parker] taught Jeff to drive before going on to teach Jeff's five sons. However, it is unknown as to whether Parker actually did teach Jeff to drive as he had a correct himself saying he wasn't quite that old.
Colonel Casey was also a friend of Jeff's. It is unknown as to what kind of relationship they had but it can assumed that their friendship was nowhere near as close to Jeff's friendship with Lady Penelope and Parker as Jeff kept the location of Tracy Island from her and that of the GDF, besides this, Casey respected Jeff's wishes as she was proud with his sons's heroic deeds as he was
Ring Of Fire: Part 1 revealed that he is either dead or missing in action due to The Hood's actions, with his ship having apparently sunk while he was looking for more information on the villain. An aquatic mission in Thunderbird 4 is briefly interrupted by the detection of the same type of transponder beacon (YT-88) Jeff had on his ship. Gordon Tracy quickly investigates where the signal is coming from, only to be disappointed to find out that it is not from his father's ship.
Relic saw Scott and Alan Tracy rescuing his old lunar crew mate Captain Lee Taylor stranded on the moon inside Shadow Alpha One. Taylor repeatedly spoke about his career alongside Jeff with Scott, and after being rescued and taken to Tracy Island, Taylor told the residents more stories about himself and Jeff.
Colony saw the return of Lee Taylor, and with it the revelation that Taylor and Jeff were the first two men on Mars, with Jeff's footprint having been preserved on the surface of the planet near the location that was subsequently chosen for the first Martian colony.
In Up from the Depths Part 1, a survey vehicle stalled at the bottom of the Marianas Trench and discovered TV-21, an International Rescue prototype vehicle, once flown by Jeff before it was sabotaged by The Hood and presumed lost. According to Jeff's eldest son, Scott, the TV-21 was Jeff's baby and that losing it broke Jeff's heart.
- The mother of Jeff Tracy's five children is completely unknown, and is not even referenced in the show at all.
- Jeff Tracy appears alive and kicking in every episode of the original show, voiced by Peter Dyneley. The voice recording of Peter's iconic countdown is used during the opening titles and during Thunderbird launches.
- Some fans believe the countdown returns and is used during launches because the voice is also supposed to be that of the new Jeff Tracy. If this is true, then Peter Dyneley has reprised his role from beyond the grave.