Eight surviving Gunpowder Plot conspirators were convicted at the trial in January 1606. They were arraigned for high treason at Westminster Hall on 27 January, after the plot’s leaders Robert Catesby, Thomas Percy and the Wright brothers had been killed while resisting capture.
The eight tried together were Guy Fawkes, Thomas Wintour, Ambrose Rookwood, Robert Keyes, Thomas Bates, Robert Wintour, John Grant and Sir Everard Digby. The jury found all of them guilty. Digby pleaded guilty; the others generally pleaded not guilty, although their convictions were effectively inevitable in the political atmosphere following the failed assassination attempt.
The sentence was the brutal punishment for high treason: hanging, drawing and quartering. Digby, Robert Wintour, John Grant and Thomas Bates were executed on 30 January 1606. The remaining four, including Fawkes, were executed the following day at Westminster.
The number eight refers specifically to the surviving plotters tried and convicted in 1606. It does not mean the total number of people connected with the conspiracy, which was larger, nor does it include conspirators who had already died or later-associated figures such as the Jesuit Henry Garnet.