The Pethakhuweyok, the Thunder Beings or Thunderers, are among the most prominent of the Lenape sky-spirits. Conceived as great winged beings of human-like aspect dwelling above, they bring the storms and hurl lightning; the sharp cracking thunder is said to be the younger ones and the low rumbling the old. As 'Grandfathers,' they are benevolent toward people: they are the sworn enemies of the horned underwater serpents and other monsters, which they strike with their fiery lightning-arrows, and Lenape narratives tell of the Thunderers rescuing human beings from those creatures. Their cycle of stories, including tales such as 'A Man Visited the Thunder Beings' and 'Grandfather Thunder,' is catalogued in John Bierhorst's survey of the Lenape corpus, and they figure in the ceremonial life recorded by Harrington and Speck.