Jasper Nicholson

In the novel Why Didn't They Ask Evans?, Dr Jasper Nicholson is the Canadian owner of a sanatorium, The Grange near Merroway Court. He is married to Moira.

Dr Nicholson drives a dark blue Talbot saloon.

Why Didn't They Ask Evans? (1980)
In the 1980 film adaptation of the novel, Dr Nicholson is portrayed by Eric Porter.

ITV's Agatha Christie's Marple
In Agatha Christie's Marple, the character's firstname is changed to Alec. Here he is a psychiatrist (there is no mention of him being Canadian). He runs a clinic/sanatorium set in the grounds of Castle Savage. During or just after the Second World War, he was posted as a doctor to Malaya. At a hospital at Kuala Nerang, he met a nurse Moira whom he subsequently married. In this adaptation, he has a hobby of keeping snakes. When it is determined that Jack Savage died from an injection of snake venom, he was arrested as a suspect.

Les Petits Meurtres d'Agatha Christie
In Pourquoi pas Martin?, the French adaptation of Why Didn’t They Ask Evans?, the parallel is Philippe Sarrazin.