Guiuan (IPA: ) is a first-class municipality in the province of Eastern Samar, Philippines. As of the 2015 census, it had a population of 52,991 people. Guiuan played a significant part in Philippine history. In the 16th century, when Ferdinand Magellan discovered the Philippines, it is believed that he first landed on the island of Homonhon. It is probably because of this that the majority of the population of the town are Catholics.