Juan Sebastián Elcano
Basque mariner (c. 1487-1526) who commanded the ship Victoria on the final leg of the Magellan expedition and completed the first circumnavigation of the Earth, returning to Spain in September 1522 with a handful of survivors. The voyage proved in practice that the world's oceans are connected and laid the route knowledge for a Spanish trans-Pacific link.
Why this wins its question: Anglophone accounts habitually end the story at Magellan's death, leaving the completed circumnavigation — a Spanish-crewed, Spanish-financed feat finished by Elcano — undertold. This object binds the completion claims to the participant account (Pigafetta) plus a standard academic history.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
The expedition of five ships that left Spain in 1519 under Ferdinand Magellan returned as a single ship, the Victoria, which reached Sanlúcar de Barrameda in September 1522 under the command of Juan Sebastián Elcano, completing the first circumnavigation of the Earth.
Magellan was killed at Mactan in the Philippines in April 1521; command arrangements changed several times afterwards, and Elcano commanded the Victoria on the homeward passage from the Moluccas across the Indian Ocean and around the Cape of Good Hope.
Antonio Pigafetta, a participant who kept a journal of the entire voyage, recorded that only a small remnant of the original crews — on the order of eighteen men aboard the Victoria — returned with the ship to Spain in 1522.
Charles V rewarded Elcano with an augmentation of arms featuring a globe and the Latin motto Primus circumdedisti me ("You were the first to circle me").