The protagonist called Ransom in C.S. Lewis’s Space Trilogy is Elwin Ransom.
Elwin Ransom is the central human character in Out of the Silent Planet, Perelandra, and That Hideous Strength. He is a philologist and university academic whose knowledge of languages becomes important when he encounters civilizations beyond Earth. In the first novel, he is abducted and taken to Malacandra, the planet known to Earth as Mars.
The surname Ransom gives the character a memorable label, but Lewis’s books identify him by the full name Elwin Ransom. The name is sometimes confused with Edwin because “Ransom” is much more prominent in summaries and adaptations.
The trilogy moves from planetary adventure to larger questions about language, morality, science, power, and spiritual corruption. Its settings and terminology draw on medieval cosmology as well as modern science fiction. Although the books are often called the Space Trilogy, they are also commonly grouped as philosophical or theological science fiction.