Zachariah Osbourne

In the novel The Pale Horse, Zachariah Osbourne is a pharmacist. He has a pharmacy on the corner of Barton Street in London. Osbourne told police he saw a distinctive looking man following Father Gorman shortly before he was beaten to death. Partway through the story, he retired as a pharmacist and moved to a house in Bournemouth which he named Everest. From there he wrote to the police saying he had attended a village fete at Much Deeping and had met one Mr Venables fitting that description. The police later told him that Venables was disabled so couldn't have been the attacker, but Zachariah Osbourne tried to give plausible explanations as to how Venables could have faked his disability.

SPOILERS AHEAD
He used the women at The Pale Horse, Mr Bradley and Customers' Reactions Classified to hide his actions. He was actually the murderer of the case and the person behind the "murder-for-payment" scheme which Jessie Davis had witnessed, and had confessed to Father Gorman.

Les Petits Meurtres d'Agatha Christie
In Le cheval pâle, the Les Petits Meurtres d'Agatha Christie adaptation of the novel, the parallel character is Lucien Cornille who similarily claims to have seen the killer of Père François.

Agatha Christie's Marple
In the Agatha Christie's Marple episode The Pale Horse, Mr Osbourne is portrayed by JJ Feild. He is also a resident of boarding house where Jessie Davis lives.