John Of Swabia, Or John The Parricide, a German prince, born in 1289, died in 1313 or 1368. He was a son of Duke Rudolph of Swabia and nephew of the emperor Albert I., the son and successor of Rudolph of Hapsburg. On attaining his majority he claimed the possessions to which he was entitled in Austria and Bohemia, but the emperor would not even surrender the county of Kyburg, which had been bequeathed to John by his mother Agnes of Bohemia. The prince thereupon entered into a conspiracy with a number of discontented noblemen, with the assistance of three of whom he murdered his uncle the emperor, May 1, 1308, near "Windisch, in Switzerland, assailing him as he was crossing the river Reuss on his way to Brugg. The murderers, who had been disguised as monks, escaped separately, and John fled to Italy, where according to some accounts he ended his life in Pisa, April 13, 1313, after having received absolution from Pope Clement V. at Avignon. But this story is doubtful, as well as that of his having spent the rest of his life as a hermit on his estate of Eigen without being recognized, and that he only made himself known at the time of his death in 1368. The emperor's daughter Agnes, the widow of Andrew III. of Hungary, and her mother, the dowager empress Elizabeth, being unable to lay hands on the conspirators, doomed to death thousands of their innocent relatives, friends, and vassals, destroying their abodes and confiscating their property.

One of the conspirators, Rudolph von Palm, was beheaded in the presence of Agnes and Elizabeth, with 63 other knights and their armbearers, while Agnes held a wreath of roses in her hand and exclaimed exultingly that "she was bathing in the dew of May," referring to the shedding of her father's blood on the first of May. Rudolph von der Wart, another conspirator, having been surrendered by the Burgundian count Blamont, to whom he had fled, was broken on the wheel after having been submitted in his wife's presence to fearful tortures. Part of the proceeds of her victims' estates was appropriated by Agnes toward the establishment of the nunnery of Konigsfelden, on the site where her father had been slain, and where she died, May 13, 1364, but without having been able to satiate her revenge on John himself. He was however outlawed by her father's successor, Henry VII. of Luxemburg. Schiller introduces John in his Wilhelm Tell.