Katherine Anne Austen, more commonly known as Kate, is one of the middle section survivors from the crash of Oceanic Flight 815 in 2004.

Kate was born in Iowa to an abusive father whom she eventually killed when she was finally of age to run and take care of herself. Kate was pursued for three years by the U.S. Marshall and was in his custody when she crashed on the Island.

On the Island, Kate formed strong bonds with Jack and Sawyer, becoming an integral member on several A-Missions. She became engaged to Jack after the rescue, but their relationship soon ended. Resourceful, quick-witted and mysteriously reclusive, she participated in many rescue and combat missions against the Others by using her tracking skills and natural ease at using firearms. In the aftermath of her very public trial for murder and other charges, Kate agreed to 10 years' probation with the condition that she must remain in the state of California. Aaron Littleton lived with her and believed that Kate was his mother until 2007 when Kate decided to go back to the island. Because of this Aaron was reunited with his biological family when Kate confessed the lie to Carole Littleton and told her about crash, Claire's pregnancy, her disappearace and to whom Aaron really belonged. Kate then told Carole that she was returning to the island to find Claire and bring her home to Aaron. Kate boarded Ajira Flight 316 and returned to the Island without Aaron. Stranded in 1977 with her friends, she worked for the DHARMA Initiative as a mechanic, and was responsible for saving a young Benjamin Linus's life. After the detonation of Jughead by Juliet, her fate is currently unknown.