Haggard is best known for King Solomon's Mines and She, which introduced the 'Lost World' genre to literature. His stories, often set in Africa, featured the iconic adventurer Allan Quatermain and blended action with elements of folklore and mysticism. His work was immensely popular in late-Victorian England, reflecting the fascination with imperial expansion and the unknown. His storytelling influenced writers like Rudyard Kipling and later creators of adventure fiction and cinema.