Oh, and as to Poirot's actual appearance:

"He was hardly more than five feet four inches but carried himself with great dignity. His head was exactly the shape of an egg, and he always perched it a little on one side. His moustache was very stiff and military. Even if everything on his face was covered, the tips of moustache and the pink-tipped nose would be visible.

The neatness of his attire was almost incredible; I believe a speck of dust would have caused him more pain than a bullet wound. Yet this quaint dandified little man who, I was sorry to see, now limped badly, had been in his time one of the most celebrated members of the Belgian police." That's according to Col. Arthur Hastings, who ought to know

Poirot has dark hair, which he dyes later in life (though many of his screen incarnations are portrayed as bald or balding), and green eyes that are repeatedly described as shining "like a cat's" when he is struck by a clever idea
Among Poirot's most significant personal attributes is the sensitivity of his stomach:

According to The Mysterious Affair at Styles, Poirot is 5 feet, 4 inches tall. He rests his egg-shaped head a little on one side. He has a "stiff and military" black moustache, which he delights in. Poirot also has the strange habit of always wearing patent-leather shoes, even when they cause him lots of pain. He usually wears a suit, and is not in great shape, since he rarely exercises.
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