Catherine Langford, the daughter of Professor Langford, was a child when her father discovered the stargate in Giza in 1928. In 1945, she was 21 years old and engaged to Ernest Littlefield, a scientist who worked with her father conducting experiments on the stargate as part of the war effort. When Ernest was lost through the stargate, the program was abruptly shut down and all records sealed.
In August of 1969, Catherine, a respected scientist in her own right, was living in New York City. Carter and Daniel, posing as the son of her father's friend and partner, Heinrich Gruber, visited her there when they were sent back in time, and they sought her help to return home. It may have been this visit that once again sparked Catherine's interest in the stargate project. She began her research again and petitioned several administrations to reactivate the program. Nearly 25 years later it was Catherine who sought out Daniel Jackson to join the stargate project, leading to the first mission to Abydos. Although she retired after the Abydos mission, she maintained contact with Daniel and the SGC, and she was reunited with her fiancé when she joined SG-1 on the mission to P3X-972 to recover Ernest Littlefield fifty years after he was lost.
Catherine was known to the SGC in an alternate reality as well. When Daniel was drawn into a parallel universe through the quantum mirror on P3R-233, he arrived in a world in which Catherine had supervised the translation team that had originally opened the stargate, and she had remained active with the stargate project after the initial mission. Catherine gave her life to defend the base against a Goa'uld attack and to send Daniel back through the stargate with a warning that would save the Earth in his reality from a similar fate.
In the eighth year of the Stargate Program, Catherine Langford passed away. She had thought of Daniel as a son, and she bequeathed her extensive research to him, which her niece, Sabrina Gosling, arranged to have delivered to the SGC. Among her possessions was an original 1889 edition of the rare book, "The Eye of the Sun," the only one known to be in existence, which detailed the customs and rituals observed by the ancient worshippers of the sun god, Ra. One of the illustrations was a reproduction of a wall painting discovered by German archaeologists in 1885 but destroyed in a museum fire ten years later, which showed a figure holding what appeared to be a zero point module, a religious icon referred to by worshippers as "The Heart of Light." This indication that a ZPM had been present on Earth during Ra's reign led SG-1 to use the Ancient time travel device to journey 5000 years back in time to retrieve the ZPM.
At Catherine's funeral, Daniel spoke of her invaluable contributions to humanity: "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."
Portrayed by: Elizabeth Hoffman, Nancy McClure, Glynis Davies