The star, who is believed to have had cancer, died "peacefully at home" on Saturday (25Jun11), according to her agent.
Tyzack was an established classical stage actress and won two Olivier awards and a Tony award for her work. She is best known for her role as Winifred on U.K. TV's The Forsyte Saga.
She played Sir Derek Jacobi's mother Antonia in I, Claudius and starred in two Stanley Kubrick films, 2001: A Space Odyssey and A Clockwork Orange.
Tyzack appeared in Britain's long-running soap Eastenders in April (11), but had to drop out due to health reasons.
She was made an Officer of the Order of the British Empire (OBE) in 1970 and became Commander of the Order of the British Empire (CBE) in the 2010 New Year Honours.