Haggard is widely regarded as a pioneer of the "Lost World" literary genre. His breakthrough came with King Solomon's Mines (1885), a thrilling tale of treasure hunting in unexplored Africa featuring the legendary hunter Allan Quatermain. The novel was an immediate success and became one of the most popular adventure stories of its era. He followed this triumph with She (1887), his masterpiece chronicling the journey of Horace Holly and Leo Vincey into the heart of Africa, where they encounter the immortal sorceress queen Ayesha. The sequel Ayesha (1905) continued her story. Other notable works include Allan Quatermain (1887), Cleopatra (1889), and Montezuma's Daughter (1893).
Haggard's vivid imagination and fast-paced storytelling influenced later writers such as Edgar Rice Burroughs and Arthur Conan Doyle. He was knighted in 1912. His novels remain classics of Victorian adventure literature, celebrated for their excitement and imaginative power.