C.S. Lewis’s childhood dog was named Jacksie. Lewis and his brother Warren adopted the name from the dog, who was killed in a road accident when Lewis was young.
After the dog’s death, Lewis reportedly refused to answer to the name Clive and insisted on being called Jacksie. The name later developed into “Jack,” which became the familiar name used by friends and colleagues throughout his adult life.
This episode is frequently included in biographies because it explains why a writer formally known as Clive Staples Lewis was commonly called Jack. “Jack” was not his legal first name, and it was not originally chosen as a literary pseudonym.
The story also belongs to Lewis’s early family life at Little Lea in Belfast. It should not be confused with the name Jack used by fictional characters in his books or with the names of later pets associated with Lewis’s household.