Hercule Poirot series by Agatha Christie.

My most favorite books ever. Read most of them. Agatha Christie wrote her first novel The Mysterious Affair at Styles in it she introduced Hercule Poirot a little Belgian Detective who became the most popular detective after Sherlock Holmes. Poirot thinks of himself as the best and brags about it. Hates sea voyages, makes him sea sick. Unlike Sherlock Holmes who solved cases by deduction, Hercule Poirot solved cases by understanding the psychology of a person.