Who is the frequent companion of Hercule Poirot in Agatha Christie's novels?

Captain Arthur Hastings is Hercule Poirot's frequent companion in Agatha Christie's novels. Hastings is a former British Army officer, Poirot's lifelong friend, and the narrator of many stories featuring the Belgian detective.

The pair first appear together in The Mysterious Affair at Styles, Christie's first published novel, although the story explains that they had met earlier in Belgium. Hastings provides a strongly contrasting personality to Poirot: he is brave, loyal, traditional, and observant, but often impulsive and less intellectually precise than his friend. Poirot sometimes teases him for his assumptions, yet Hastings's apparently casual observations occasionally help solve a case.

Hastings is often compared with Dr Watson, Sherlock Holmes's companion and chronicler. He appears in eight Poirot novels and several short stories, but is absent from a long middle period of the series. After marrying Dulcie Duveen, Hastings moves to Argentina, though he returns for later cases, including Curtain: Poirot's Last Case. Colonel Race and Inspector Japp are recurring Christie characters, but neither is Poirot's defining companion.