Raymond West is a fictional character who appears in several of Agatha Christie's novels featuring Jane Marple. He is a well known author and Marple's nephew. He is not interested in Marple's cases. But in some novels (like A Caribbean Mystery and At Bertram's Hotel) he supports Marple financially. His wife Joan (née Lemprière), an artist, is also sympathetic to Marple.
In The Thirteen Problems, his future wife's name was given as Joyce, not Joan. Raymond's mother was one of three girls, with Marple being the eldest and his mother having another sister. This other sister had a daughter, Raymond's cousin Mabel Denman, who was accused of murdering her husband, Geoffrey (The Thirteen Problems).
Raymond and Joan had two sons, one of whom is named David and works in British Railways. David was able to help his great-aunt solve a mystery regarding a missing corpse by sending her a map of a certain patch of railway (4.50 from Paddington). His other son, Lionel, is a keen stamp collector and has shown Miss Marple every single one, and told her about the rare 1855 Blue Stamp, which helps her solve a case regarding a lost inheritance (Miss Marple's Final Cases and Two Other Stories).