St. Brendan, also known as St. Brendan the Navigator, was an Irish monk and explorer who lived during the 6th century. He is best known for his legendary voyage across the Atlantic Ocean, which is detailed in the medieval text called the Navigatio Sancti Brendani. This journey is often considered one of the earliest accounts of transatlantic exploration. St. Brendan founded several monasteries in Ireland and is recognized as one of the early Christian missionaries. His feast day is celebrated on April 16, and he is the patron saint of sailors and travelers. His life and adventures have inspired many stories and legends throughout the centuries.