Annika Hansen and her family were assimilated by the Borg when she was still a young child, in 2348. Her mother and father were famous Federation scientists. They took their ship, the S.S. Raven NAR-32450, and headed toward the Delta Quadrant to conduct scientific research and were never heard from again. After assimilation she became known by the designation "Seven of Nine, Tertiary Adjunct of Unimatrix Zero-One". Seven of Nine's interplexing beacon has a translink frequency of 108.44236000.

In 2374, Seven of Nine became the liason between the Borg and the U.S.S. Voyager during a joint operation to defeat Species 8472. In exchange for information about Species 8472, the Borg were to grant Voyager safe passage through the vast Borg space. Seven of Nine joined the Voyager crew when her connection to the Borg Collective was severed after her Borg cube was destroyed by Species 8472 bioships. Voyager's EMH Doctor removed many of the Borg implants and her human characteristics are resurfacing. Seven currently has approximately 18% of the Borg implants still functioning, including her cranial and occular implants. Even though she is becoming more human, she prefers to be called Seven of Nine, and not Annika.

Starfleet History
2374 Acts as Liason between Borg and U.S.S. Voyager.
2374 Disconnected from Borg collective by Voyager crew.
2374 Designed a new Astrometrics Lab with Ensign Harry Kim.
2374 Successfully traversed radioactive nebula while crew was in stasis.
2375 Assisted with construction of The Delta Flyer.
2375 A Borg Vinculum causes Seven to manifest multiple personalities.

Seven of Nine was first seen in "Scorpion, Part II" (VOY).