Who is Leslie and then there were none?

Answer 1

Leslie is the General's wife who was having an affair with Authur Richmund. The general killed Authur, and Leslie, later, died of pneumonia.

Answer 2

Leslie is not a character in Agatha Christie's novel "And Then There Were None." The main characters in the book are a group of individuals invited to a remote island who are mysteriously killed off one by one.