In 'Frankenstein', what is the name of the Arctic explorer who writes letters?

In Mary Shelley's Frankenstein, Robert Walton is the Arctic explorer who writes the novel's opening and closing letters.

Walton addresses his letters to his sister, Margaret Saville, while commanding a ship on an ambitious voyage toward the North Pole. He hopes to discover unknown lands and reach regions no previous explorer has charted. His loneliness and desire for intellectual companionship establish the novel's themes of ambition, isolation, and dangerous discovery.

During the expedition, Walton's crew encounters Victor Frankenstein, exhausted and nearly frozen while pursuing the Creature across the Arctic ice. Victor then recounts his life story to Walton, creating a framed narrative: Walton's letters contain Victor's account, which in turn includes the Creature's own narrative.

A common mix-up is calling Victor Frankenstein the letter writer because his story occupies most of the novel. Victor is the scientist and central narrator within the frame, while Walton is the outer narrator. Walton's decision to turn his ship around after hearing Victor's warning also provides a crucial contrast between destructive ambition and the possibility of restraint.