Eu não tenho certeza desde 1996, mas o Cackler é oficialmente nomeado e introduzido no suplemento de 2000 The Black Circle: Unholy Alliance.
Veja a reimpressão do pdf aqui:
Citação do texto promocional:
Marshals will get their first hints of a major new force in the Weird West: the Cackler!
Aqui está um resumo do que é dito sobre o Cackler neste suplemento.
Alerta de spoiler! (texto suspenso abaixo)
The Cackler is an ancient lich from England, a kind of English counterpart to Stone. He pre-dates the Reckoning, though his power has benefited from it. He is a surviving son of an ancient sorceress, the sorceress also being an ancestor of the Whateley Clan. In the Black Circle supplement, the Cackler has got Mina (who encountered him on a visit to England) and the Wichita Witches tracking down the descendent who is foretold to carry his mother's spirit. The supplement is pretty clear however that Marshals should not introduce the Cackler directly—he should rather be a force behind the scenes, as he has some big evil purpose in the future of the setting.