- "Catherine Langford was more than just kind and generous. She had a gift of an endless, open-minded, child-like curiosity. She saw the world not for what it was, but for what it could be, and she saw potential in people that others failed to recognize. Like her father before her, her contributions to science have changed the world more than most people know. I, for one, have no idea where I would be today if I'd never met her. She changed my life in more ways than I ever could have imagined."
- ―Daniel Jackson at Catherine Langford's funeral.[src]
Catherine Langford was the daughter of the archaeologist Professor Paul Langford. She dedicated her life to unraveling the mystery of what would become known to Earth as the Stargate, a device she witnessed her father discover in Giza in 1928.
Much of Catherine's life was influenced by the discovery of the Stargate, which her father made on the Giza plateau in 1928 when she was a young girl. It was at the Stargate's excavation site where she discovered an Eye of Ra medallion - a deeply cherished item that she would wear for the rest of her life. (Stargate)
Catherine and her father have been studying the Stargate for some time, but up to that point they had been unsuccessful in learning what it is or what its purpose is. During this time, she had met James Beal, a captain in the British Military, at a market and was involved in a romantic relationship with him. He later went through the Stargate with her to help her rescue her father.
Catherine's father and her fiancée, Ernest Littlefield, did experiments on the Stargate in 1945. Catherine's father told her Ernest had died in an accident, but in reality he traveled through the mysterious ring to another planet and was presumed lost. (SG1: "The Torment of Tantalus")
In 1969, Catherine received a brief visit from two strangers, one of whom claimed to be the son of Heinrich Gruber, her father's partner in the original dig in Giza and researcher on the Stargate in 1945. She was able to tell her visitors where the Stargate was currently being stored. In reality, the visitors were Captain Samantha Carter and Dr. Daniel Jackson who, along with Teal'c and Colonel Jack O'Neill, had been accidentally transported back in time. It's possible that Jackson and Carter's visit prompted Catherine to begin pressing the military to reopen its research on the Stargate. By this time, her father had died. (SG1: "1969")
In 1996, she hired Daniel Jackson, this time fully aware of who he was, to re-translate the texts discovered with the strange ring. It was Daniel who discovered that the artifact was called a Stargate. Later, through linking star signs with glyphs on the object, Daniel made the intuitive leap that made it work for the second time, which was the first time as far as Catherine or anyone else involved in Project Giza knew. She gave Daniel the Eye of Ra medallion for good luck when he went through the gate. Catherine said that she had no desire to travel through the 'Gate herself – now that she knew what it was for and how it worked, she felt "complete".
Although Daniel remained behind on the other side of the Stargate, he sent her medallion back with O'Neill, asking him to tell Catherine "it brought [him] luck." (Stargate)
In 1997, Daniel discovered the Stargate had been successfully activated in the 40s and went to visit Catherine for answers. She was pleased to see Daniel, and confirmed for the first time that the Eye of Ra had been returned to her. Upon realizing that Littlefield might still be alive, she accompanied SG-1 to the planet Heliopolis. Once there she was reunited with Ernest and they traveled back to Earth together. (SG1: "The Torment of Tantalus")
Catherine died in 2005. Daniel gave an eulogy at her funeral that was well received by her niece, Sabrina Gosling. Sabrina said that Daniel was like a son to Catherine, and returned the Eye of Ra medallion to him. Gosling later arranged for Daniel to receive the rest of his inheritance from Catherine, which, much to his shock, turned out to be her entire collection of artifacts. Catherine's legacy turned out to have one more boon, as her collection ultimately led to the discovery of a Zero Point Module which was instrumental in saving the Atlantis expedition. (SG1: "Moebius, Part 1")
- In an alternate reality visited by Daniel Jackson in 1998, Dr. Catherine Langford attempted to recruit the Daniel Jackson of her reality into the Stargate Program. However, he rejected her offer and she described him as being "quite rude" in doing so. She supervised the team that discovered how to make the gate work and Jack O'Neill led the first mission through the Stargate to Abydos. She continued to head the SGA until Apophis's forces invaded Earth in 1998. She was killed in the invasion of Cheyenne Mountain. When Daniel thanked her for helping him get home, she said since he helped the Catherine from his reality reunite with Ernest Littlefield, she considered them even in the grand scheme of things. (SG1: "There But for the Grace of God")
- Catherine claims to have been 21 years old in 1945, placing her birth in 1923 or 1924. This would mean she was four or five years old at the discovery of the Stargate in 1928, 44 or 45 when meeting with a disguised Sam and Daniel in 1969, and 81 or 82 at her death in 2005.
- Catherine Langford was the focus of the series Stargate Origins.