With the exception of Guy Fawkes, who was recruited for his knowledge of sieges and explosives, the plotters were related to each other; indeed, the pressure of family ties were important in the recruitment process. Interested readers should consult Antonia Fraser's book The Gunpowder Plot, which contains family trees.
The Original Five
Robert Catesby
John Wright
Thomas Wintour
Thomas Percy
Guido 'Guy' Fawkes
Recruited before April 1605 (when the Cellar was filled)
Robert Keyes
Thomas Bates
Christopher 'Kit' Wright
John Grant
Robert Wintour
Recruited after April 1605
Ambrose Rookwood
Francis Tresham
Everard Digby