Kate Box is an Australian stage, film, and television actress. She is known for her roles as Nicole Vargas in Rake, Lou Kelly in Wentworth, and as Dulcie Collins in Deadloch.

Kate Box grew up in Adelaide, South Australia. She lived with her parents, social workers Greg and Lorraine, and sister Sally in Colonel Light Gardens, and attended the local primary school.

She did her secondary education at Annesley College. At the age of 13 she started classes at Unley Youth Theatre (now Urban Myth), where she met filmmakers Sophie Hyde and Matthew Cormack, who went on to form Closer Productions, and screenwriter Drew Proffitt.

Box started a bachelor of arts degree at the University of Adelaide aged 17, intending to major in psychology, but changed her mind and graduated with politics and Australian studies as her major subjects. She then auditioned for the Victorian College of the Arts and National Institute of Dramatic Art (NIDA). She was accepted into NIDA course and, at the age of 22, moved to Sydney. She graduated from NIDA in 2003.

Her first stage performance was in 2004 as Helena in A Midsummer Night's Dream at the Bell Shakespeare Company. Her role in the Sydney Theatre Company presentation of Top Girls earned her a Helpmann Award for Best Female Actor in a Supporting Role in a Play nomination in 2018. Other stage credits include Dolores (Old Fitzroy Theatre), Macbeth (Sydney Theatre Company) and A Christmas Carol (Belvoir).