|Name||changes frequently: Sigourney, Kasandra...|
|Age||13 - 14|
|Physical appearance||thin, red hair, probably scowling|
|Books||Only You Can Save Mankind, Johnny and the Bomb|
Kirsty is a friend of Johnny Maxwell. Unlike the rest of his friends, she is a winner, but in such a way as to have difficulty making friends, which results in her suspecting a character flaw in everybody else.
She has already scared off all comers at the karate club, earned medals and cups in all manner of sports and been moved three or four years ahead at school, but she can be quite clueless in some ways. As Johnny puts it, "There were two kinds of stupidity, the basic El Thicko sort that he had, and another kind that came from being stuffed too full of intelligence." Like many bright but naive youngsters, Kirsty firmly believes in all sorts of paranormal mumbo-jumbo and conspiracy theories, presumably because it pleases her to think that she knows more than she's meant to.
She is also terribly organised, and given to organising everyone else, while telling them, for their own good, how stupid they are. As Yo-less puts it, "She keeps looking at me as if I've answered a question wrong".
Kirsty first appears in Only You Can Save Mankind where she chooses to call herself Sigourney and re-imagines the game universe into something out of Alien. She is absent from Johnny and the Dead, but takes such a large role in Johnny and the Bomb that she considers it to be an adventure of her and four token boys. For most of the story she calls herself Kasandra, having continued with the habit of renaming herself at frequent intervals.