An unfortunate maid working at Unseen University who appears to be first in line for any risks over and above the job description.
As if this is not enough of a life-changing encounter, in Moving Pictures she is the one who first realises the vase in the corridor is spitting out lead pellets at a life-threatening velocity, and who is dragged in front of Mustrum Ridcully by Mrs Whitlow to explain what has happened.
The original Cassandra was the prophetess of doom in ancient Troy. She was doubly cursèd by the Gods in a manner reminiscent of Agnes Nutter. The nature of the divine curse was that (i) she would always get it right and be an infallible prophetess; and that (ii) nobody would listen. The net result was that when she started tuning in to the idea that the Greeks had worked out a method of getting inside the walls of Troy, nobody listened to her warning - "oh, it's just that loony woman again" - and the city duly fell.