The 75-year-old actress, who played Sue Ellen Ewing in both incarnations of the US soap, will play the mother of Lysette Anthony's character Marnie Nightingale in the Channel 4 programme, reported Contactmusic.
"I'm thrilled to be going from one iconic series to another," said Gray, promising her character, Tabby, would "whip up a storm just like Sue Ellen did".
Gray appeared in the first episode of "Dallas" in 1978 and went on to appear in more than 300 episodes. She reprised the character when the show was briefly revived in 2012.
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