Katherine Chambers

 was a childhood friend of Peri Brown and as an adult a friend, and doctor to Tegan Jovanka.

When Peri returned to Baltimore after finding out about Anthony Chambers' murder, Kathy hadn't seen Peri for four months. In the meantime her grades had improved enough to get into medical school. During the siege of Anthony's undertaking offices, she was appalled at cyber converted Anthony's distress. His attack on Nathaniel Chambers paralysed him and made her despise The Doctor (BFA: The Reaping)

While at university she met James Clarke, who was interested in the cyber conversion unit left by Peri at her home. The piece left behind killed Janine Foster and Dominique van Gysegham. She blamed herself for their deaths. (BFA: The Reaping, The Gathering)

She moved with a partially converted Nate and James, to Brisbane because of Janine's death. She founded Chamber's Pharmaceuticals, where she planned to find cures for cancers and other diseases. When a different Doctor came asking about alien technology, she took him to the bar 8687, where he met Tegan. She used the cyber conversion technology to create a system to cure any disease. Tegan was to be its first patient. However The Doctor persuaded Nate to destroy it, killing himself. This was yet another death that Kathy blamed herself for. (BFA: The Gathering)