Orac is a fictional character from the British science fiction television series Blake's 7. The voice of Orac was provided by Peter Tuddenham.



Orac is a highly advanced supercomputer developed by the scientist Ensor, brought aboard the Liberator by Blake and the others at the end of the first series. Ensor was a particularly irascible character and Orac, as his creation, inherited some of his character traits. It is extremely terse and short-tempered. Orac has the ability to communicate with all other computers that carry tarriel cells and hence provide the Liberator crew with valuable knowledge. Through calculation of probability, Orac can predict the future as seen in the series 1 cliffhanger episode (also called "Orac") in which it predicts the destruction of the Liberator. Orac's systems are multi-dimensional; it projects a carrier beam through the same dimension that allows telepaths to transfer thoughts. It is through the hijacking of this beam that an unnamed psychic being attempted to invade the physical plane. It was defeated through Cally's telepathy boosted by proximity to telepathic plants called Moondiscs. To prevent any future incursion by the being, Avon fitted a bomb to Orac that would detonate if its power fluctuated outside of its normal parameters.

This is not the last time that it has endangered the crew. Its desire to study a black hole was so great that it took control of the Liberator and steered it far too close. It seems that if its curiosity is piqued it will endanger itself and others. It states that gaps in its knowledge are "Intolerable".

Orac is presumably a contraction of Oracle. Another theory is that is short for ORal ACknowledgement, referring to Orac's spoken responses. Yet another theory is that because of Orac's ability to communicate with computers that have tarriel cells (ie most computers in the known universe), ORAC is short for Operate and Read All Computers.