In the NHK adaptation ABC Murders, Episode 5-8 of their anime series Agatha Christie's Great Detectives Poirot and Marple, the portrayal of Thora Grey is fairly close to that in the original book but the voice actress behind the character is not credited.
In the MGM adaptation The Alphabet Murders (1965), Sir Carmichael Clarke did not have a secretary.
In the 2018 The ABC Murders miniseries produced by BBC, Thora Grey was portrayed by Freya Mavor. Here she has a backstory. She arrived in the Clarke estate as an orphan but then started to cause what Lady Clarke called 'problems'. Here she is fired by Charlotte Clarke before Carmichael's death and not after, when she makes a scene at dinner. In this adaptation Thora is somewhat of an accomplice of the killer of the case. She strongly dislikes a Nurse Carstairs who looked after Lady Clarke. This does not happen in the original novel. When Clarke is killed, Inspector Crome claims there must have been an error because ABC killed only women. He then suggested that Thora could have been the intended victim and that the killed would have thought her last name was Crey and not Grey. Miss Grey replies that the killer could have just simply murdered Nurse Carstairs instead.