Miss Grey is described as being tall and slightly masculine. She is dressed in tweed, has grey hair and a large beak nose. Her penetrating eyes are light blue, and she speaks with a hearty bass voice.
- In the 1997 ITV adaptation, Thyrza Grey was portrayed by actress Jean Marsh.
- In the 2010 Agatha Christie's Marple episode, Thyrza Grey is portrayed by actress Pauline Collins. In this adaptation, Thyrza and Sybil Stamfordis actually run an inn named "The Pale Horse". As described in the original novel, she was the only one of the team who actually knew the linkage of their occult activities to Mr Bradley and the "murder-for-payment" scheme although it is not clear if she knew how or who did the killing. She explained to Sybil that working for Bradley was the only way they had to pay for the inn, which had suffered after tourism to the village declined with the building of a road which bypassed the village.
- In the 2020 BBC miniseries, Thyrza Grey is portrayed by actress Sheila Atim.
- In Le cheval pâle, the French Télévisions film adaptation of the novel for the series Les Petits Meurtres d'Agatha Christie, the parallel character is actually named Sybille.