Bertie is a primary character whose life Millie narrates; he has a deep bond with a white lion cub he raises in South Africa, and later endures the challenges of boarding school in England.

Millie is a central character who recounts the story of her life with Bertie and their adventures, serving as a guiding presence for both Bertie and Michael.

Bertie's mother is an Englishwoman living in South Africa who shares a close relationship with her son and plays a pivotal role in protecting the lion cub.

Bertie's father is a strict South African cattle rancher whose decisions lead to significant changes in Bertie’s life and the fate of the white lion.

Millie's father is mostly absent from her life, playing a minor role in her upbringing and leaving her under the care of a governess and nanny.

Nanny Mason is Millie’s caring and motherly figure, providing the warmth and stability lacking from her biological parents, and remains an integral part of Millie's life.

Miss Tulips is Millie’s stern governess, known for her strictness and lack of warmth, contributing to Millie’s isolated childhood.

The white lion is a rare and cherished animal raised by Bertie in South Africa, whose journey and memorial form a key element of the narrative.

Monsieur Merlot is the kind French circus owner who purchases Bertie's white lion and develops a deep attachment to the animal over the years.